I had a v6 car that now has a olds 350 in it. The rear end gear is stock 3.8 v6 gears which Im bumping up. I want a trans for power and streetable gas mileage with higher gears and is why it has to have Over drive. Which out of the 200r4 and 400r4 is the best to use for this?

 

What car are you talking about?

 

Its a 1983 four dr cutlass with a 1972 olds 350 in it

 

The 200-4R would be closer to a bolt in. The 400r4, I think you mean the 700-4r, would require a Chevy to BOP adaptor plate....

 

Yeah really have no idea what you are talking about when you say 400R4. There is no such thing. There is 200R4, 700R4, 4L60e, and 4L80e.

200r4 is your best bet. Straight bolt on to an Olds motor and in 72 the 350 was putting out a bit lower torque, so in stock forum, you should be good.

You should buy a convertor lock up kit. You'll need it to lock the tranny in overdrive when you are cruising.

It might be in your best interest to swap the rear axle to an 8.5 instead of spending any money on that 7.5. You may get lucky and find a posi out of a 442 or GN in the local junkyards

 

As the others said, a 200 R4 would be a direct bolt in. You probably don't have to worry about upgrading any internal parts in the transmission if you keep your 350 stock.

 

Just to clarify, the names according to GM are 200-4R and 700R4. Go figure why they used a different convention.

 

Yes that 400 was a typo I didnt catch. Im just looking for something better than 350 turbo when I put 3.73s on with a differwnt rear end

 

The overdrive would be handy when you swap to 3.73 gears. Although the TH 350 is a great transmission.

 

Be aware that your V6 car probably came with a TH200C. The 200-4R requires a different crossmember - though if you are converting to dual exhaust you'll be getting one anyway. Also, your 83's frame may not have the proper reinforcement for the 200-4R crossmember. If not, you'll need to get one of these:

engineswap032.jpg

It's called a "frame extension kit" and you can get them from Summit, Jegs, etc.