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1966 Transmission?

F

fadec

Member
Hi guys. Just joined here. When looking to do an oil change on my transmission, I just found out that my 1968 Jeep J-3500 pickup that has a 1969 Buick 430 in it also has what I assume is a 1966 TH400. I'm trying to nail down just what this transmission might have come from. The data plate was sanded clean at some point in its life. All that is left are stampings. The date code is "336" with the others being "BU-66-24313". This transmission also has a P/N 8623569 valve body (used on both Buick's and Jeep TH400's)

I was not able to find any info on Jeep TH400 Trans codes. Since this is mounted to a Buick engine, with a BOP case, I figured might as well start with the Buick codes. Could the BU coded trans have been installed on both Jeeps and Buick's? Or do I most likely have some sort of Frankenstein trans that is adapted to mount the Dana 20 transfer case on on end and a big block on the other with a Jeep valve body in between? So far the Jeep forums have come back with nothing.
 
Thanks for the reply! Is there a way to confirm if I have a switch pitch converter on this trans without tearing it down?

Jeep did offer a Buick 350 a few years after mine was built, after AMC bought Kaiser in 1970, but never a big block. This is definitely a swap that occurred early in the jeeps life. Everything I've found on the 430 so far is date coded from 1969. The corrosion is so bad I'm not able to read the vin, but I'm confident from all the other codes I've found, it truly is a '69. It just seems odd they would use a 1966 BU trans for a truck. I wonder if they were trying to get the benefits of the switch pitch feature for this big block? I have found no extra wiring going to this trans other than the kick down switch. Also, could it still handle the torque of the big block?

The truck VIN says it was born with a V8, but not exactly which. Most likely either an AMC-290, 343 or 390 respectively. From what I've found tonight is that these AMC engines did not have the same bolt pattern as anything else on th planet. Such as why it was so popular to swap them out. I can only speculate on why they did with what they did with half the crap I've found on this truck so far.

This is starting turn into a CSI investigation just to figure out what I have! All this just because I wanted to change the oil filter in my trans. 🧐
 
Kaiser used Buick v6s ( beginning with the 225ci in 1966 for the CJ and C101 models ) and 350s ( Gladiator and Wagoneer ) for several years in the late 60s, it was AMC that killed that off in favor of their own engines in 1971 ( the merger happened in 1970 and AMC wasn't ready to kill them the first year ). Buicks used in Jeeps were marketed under the term "Dauntless" for both the 225 and 350 applications.


Jeep Engine: Dauntless Buick 350 V8

All about the Jeep Dauntless Buick 350 V8 engine.
www.jeeptech.com

en.wikipedia.org

Buick V6 engine - Wikipedia

en.wikipedia.org en.wikipedia.org

the interesting thing about the 225 and 350 being that ... they share the same transmission bellhousing with the big block Buick engines ( 400, 430, 455 ). they also share most of the other major design layout as the big blocks, such as forward mounted distributor and oil pump, fuel pump placement, clutch throwout placement, etc.

thus, where it will fit, a BBB will be a favored swap for a Dauntless engine due to the simplicity of install. you should really only need engine mounts and a big block fan shroud and any other mods will be pretty simple and incidental.


Also, could it still handle the torque of the big block?

all an ST-400 ( for Super Turbine ) is, is a TH-400 ( for Turbo Hydramatic ) with a Switch Pitch convertor. most times.

most of the parts in a TH-400 rebuild kit can be used in an ST-400.

it can handle it.


I have found no extra wiring going to this trans other than the kick down switch.






From what I've found tonight is that these AMC engines did not have the same bolt pattern as anything else on th planet.

i'm not sure i remember exactly how it goes, but there's something really stupid with the AMC sourcing transmissions from GM and Chrysler thing. i THINK that there was something about some AMC installations being a Nailhead to Chrysler pattern so you can get an A-727 in there? something silly like that.
 
fadec said:
Hi guys. Just joined here. When looking to do an oil change on my transmission, I just found out that my 1968 Jeep J-3500 pickup that has a 1969 Buick 430 in it also has what I assume is a 1966 TH400. I'm trying to nail down just what this transmission might have come from. The data plate was sanded clean at some point in its life. All that is left are stampings. The date code is "336" with the others being "BU-66-24313". This transmission also has a P/N 8623569 valve body (used on both Buick's and Jeep TH400's)

I was not able to find any info on Jeep TH400 Trans codes. Since this is mounted to a Buick engine, with a BOP case, I figured might as well start with the Buick codes. Could the BU coded trans have been installed on both Jeeps and Buick's? Or do I most likely have some sort of Frankenstein trans that is adapted to mount the Dana 20 transfer case on on end and a big block on the other with a Jeep valve body in between? So far the Jeep forums have come back with nothing.
Click to expand...
Attached is a Clutch Plate Chart from GM's 1971 TH400 & 425 Troubleshooting Manual.
The brand usage of the models noted can be decoded from the first letter as:
A = Cadillac
B = Buick
C = Chevrolet
K = Jeep (Kaiser)
O = Oldsmobile
P = Pontiac
R = Rolls-Royce

This corresponds to the '74 Chilton manual which indicates Buick engines supplied for Jeeps had a first letter of K on the ID code stamped on the block.

Interestingly the clutch packs used in the noted Jeep codes KJ. KK, KL, KM are lighter duty than those used on most other brands. My thought is the Jeeps would not have been built with Buick B* code transmissions.

According to this vendor's site adapting a TH400 to a transfer case on the larger Jeeps is not that big a deal

The Novak Guide to the GM TH400 Automatic Transmission

The Novak Guide to the GM TH400 Automatic Transmission
www.novak-adapt.com www.novak-adapt.com


Here is a thread from another forum discussing the Jeep transmission applications:

www.v8buick.com

tranny code kj on nailhead turbo hydromatic

what year is this tranny code? tag reads: kj-69-2502. Will this tranny bolt up to a 65 nailhead motor. Thinking about a motor tranny swap for my 63...
www.v8buick.com www.v8buick.com
 

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fadec said:
Thanks for the reply! Is there a way to confirm if I have a switch pitch converter on this trans without tearing it down?

Jeep did offer a Buick 350 a few years after mine was built, after AMC bought Kaiser in 1970, but never a big block. This is definitely a swap that occurred early in the jeeps life. Everything I've found on the 430 so far is date coded from 1969. The corrosion is so bad I'm not able to read the vin, but I'm confident from all the other codes I've found, it truly is a '69. It just seems odd they would use a 1966 BU trans for a truck. I wonder if they were trying to get the benefits of the switch pitch feature for this big block? I have found no extra wiring going to this trans other than the kick down switch. Also, could it still handle the torque of the big block?

The truck VIN says it was born with a V8, but not exactly which. Most likely either an AMC-290, 343 or 390 respectively. From what I've found tonight is that these AMC engines did not have the same bolt pattern as anything else on th planet. Such as why it was so popular to swap them out. I can only speculate on why they did with what they did with half the crap I've found on this truck so far.

This is starting turn into a CSI investigation just to figure out what I have! All this just because I wanted to change the oil filter in my trans. 🧐
Click to expand...
If there are two spade terminals coming out of the electrical connector on the left side of a '66 TH400, it has the switch-pitch feature.

The old Chilton's manual indicates the only V8s available on '68 Jeeps were the Rambler 327 and the Buick 350. Some sources indicate the Buick 350 wasn't available for Jeeps until '69. My books aren't that good on Jeep data. I think somebody removed the original engine and trans and replaced them with the '69/66 Buick setup.

Finding the correct filter shouldn't be a problem. Here is the page from the '71 GM manual showing the early TH400 filters.IMG_1439.JPG
 
TODD said:
If there are two spade terminals coming out of the electrical connector on the left side of a '66 TH400, it has the switch-pitch feature.

I think somebody removed the original engine and trans and replaced them with the '69/66 Buick setup.
Click to expand...

Yes, the one thing I've known since I bought the truck is that this in not the original engine/trans combo that it came with. The transfer case and both axles do appear to be original to the truck. Though many say my Dana 53 rear axle was not offered on this model '68 Gladiator, but an old dealer told me this axle was offered as an option (dealer installed) during those years. He agreed that the axles are most likely original.

I did step out to the shop this morning and confirmed I have both two spades on the kick down connector and also the three dimples on the pan. I do have a SP. Now to complicate matters, if they did have it hooked up at one point it is no longer there. As ALL the wiring to the trans is missing. Not even a kick down wire. I see no evidence of a separate switch for the SP on the dash and the carburetor has no SP switch either, as it was replaced a few years ago by the previous owner with a Edelbrock carb. The previous owner had no clue at all of what he had, nor did he even try to find out. In the end he did more damage to this truck than any good.

From a few other articles I read over the last 12 hours... this 430/SP trans combo can be a really nice setup. Now that I know what I'm looking at, it's time to start planning just how I want to make it all work again. I already know this Gladiator is going require a 100% re-wiring. With that, I'll need to insure I have both the kick down and SP wiring/switch added to the harness when I build it up. Then also comes the rebuilding of engine/trans/transfer case.

Having a relatively rare SP trans, would it be best to have a specialist shop do the rebuild? Such as Phoenix Transmissions?
 
On SOME Jeeps with a ST400 trans. Jeep used a NailHead trans. with an adapter between the block & NailHead trans. but NOT a switch pitch. The NailHead trans. was about 2" or more shorter than a BOP patterned trans. Jeep. ALSO used the NailHead trans. behind there AMC engines for a few yrs. 1967 was the last yr. Buick used the switch pitch SP400 with a BOP patterned trans. '66 on the I.D. tag would identify it as a '66 trans. unless Jeep used an older trans. without an adapter between the engine & trans.
Good luck on finding a COMPLETE switch pitch set-up with all you'll need for the kick down & switch pitch & adapting it to your set-up.
 
telriv said:
Good luck on finding a COMPLETE switch pitch set-up with all you'll need for the kick down & switch pitch & adapting it to your set-up.
Click to expand...

Did some more poking around and found its all there with the exception of the wiring and a switch on the dash. The engine and trans have already been matched up well and everything looks to be there. The wiring will be taken care of soon. The overhaul of both the engine and trans will follow as budget allows.
 
You may want to put 12 volts to the posts on the side of the trans to make sure the solenoids are working. The rebuild is not that different from a TH 400. A shop that id good with the TH 400 should have no issue with the ST 400. The converter is the thing you want to watch out for if rebuilt. They are hard to find and it can be hard to find someone to rebuild it correctly. I would not know who to send it to currently. The rebuilders used in the past are gone.
 
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