73 Riviera trans swap

**Sled lover** · 04-06-2012, 05:22 AM

Hi guys. I want to swap out my TH350 to a 4l60 or 4l80. Will either of these options work on the 455. I know the 4l80 is based on the TH400 design. I dont know about the bolt patterns.

Thanks

Mike

**raycow** · 04-06-2012, 10:47 AM

AFAIK, the 4L80 was made only with the Chevy bolt pattern and all of them require an electronic controller. The 4th gen Camaro/Firebird was offered with the 3.8 V-6 and 4L60 for a while, but I don't know if those engines had the RWD bolt pattern, which is normal BOP like your 455, or the FWD pattern, which isn't.

Since any 4L60 would need a non-stock build in order to last for any length of time behind your 455, you may as well look at a TH200-4R, all of which have the BOP pattern. It won't cost you any more to build one of those than the 4L60.

Ray

**bob k. mando** · 04-06-2012, 06:42 PM

ray, the 3.8L that you're talking about is the major redesign "Series II" engine. they shortened the deck an inch, i'd be really surprised if they didn't convert it to the Chevy trans pattern.

http://en.wikipedia.org/wiki/Buick_V6_engine#Series_II

**raycow** · 04-07-2012, 10:12 AM

Bob, thanks for chiming in on this one. I haven't been able to get a close enough look at one of those Camaro 3.8s to see which bellhousing bolt pattern it used.

Ray

**Warden** · 04-08-2012, 08:22 AM

The 200r4 built correctly will handle incredible abuse. It is dimensionally the same as st300, powerglide and th350. Driveshaft length and yoke are the same as well. I used bowtie overdrive for the tv cable and lockup. B&M also offer a speedo based lock up. I had mine built local in Denver with lockup convertor for $800. I couldn't be happier with mine.

**Sled lover** · 04-08-2012, 01:22 PM

Thanks for all the input on the trans swap guys. I was looking at a tci 4l80 and a tci adapter plate. I like the direct bolt better. I picked up at 200r4 its at the trans shop now.