did the turbo 3.8 ever come with a rear other than 3.42?? I'm looking to swap rears and put a 200-4r in my 75 century oddfire, and I'm looking for suggestions for the rear gear to choose. I was thinking about 3.23, (just for the mileage). its got 2.73's in there now (way sluggish). and I'm planning to slap on a paxton sn-93 (5# boost) to add some pep. I dont want to make a drag car, just add some pep for my daily driver!!!!! any suggestions would be great!!! thanx, brad b

swapping in a 200r4 ( i assume you've got a TH350 now ) AND changing the rear will probably get you quite a bit on accell.

first in a 200r4 is 2.74 while in a TH350 it's 2.52, couple that with dropping 50+ points in the rear and that's going to factor a bit.

2.52 * 2.73 = 6.88 car now

2.74 * 2.73 = 7.48 200r4 installed

2.74 * 3.23 = 8.85 'mileage' gear

2.74 * 3.42 = 9.37 'drag' gear :bgrin:

simply dropping in the new trans is going to get you almost a full ratio up on your driveline ratio in 1st, swapping in either of the 3 series rears is going to make you quite impressed with your little odd fire off the line.

you may actually want to put in the 3.23 just to make sure you're not dogging the motor at highway speeds.

1.00 * 2.73 = 2.73 car now, 3rd on TH350

.67 * 2.73 = 1.83 200r4 installed, 4th gear

.67 * 3.23 = 2.16 'mileage' gear

.67 * 3.42 = 2.29 'drag' gear

otoh, you should get FANTASTIC mileage from now on.

always remember, you can 'fine tune' your final drive ratio with different height tires.

3.42 only on the TRs. Posi was optional at 100.00. All were 8.5" 10 bolts in Turbo cars. :shield:

I wish all TR came with an 8.5" rear. My 79 had a 7.5" with a 2.73 open carrier. It now has 3.08 posi. I have looked 8 years for an 8.5" and finally have found one. I pick it up next week. As far as I knew only the GN's, some T types and Olds 442 had an 8.5" from the factory.

thanx for all the info.... I just wanted to make sure the 3:23 's weren't going to be too much for the oddfire. thanx SOOOOOOOOO much you guys have been great!!! with all the help & info!!!!:hurray: thanx again, brad