** Need Transmission Advice **

[NoRest92]

Hey guys I recently dropped the THM200 transmission out of my 1985 Regal Limited and am looking into replacements. I couldn't find a similar thread so I'm hoping this will help others as well. I have a lot of questions and options so bear with me. I'm having trouble deciding between replacing it with a 200r4, 700r4, turbo 350, or having my current one rebuilt. I'm wanting better performance and if I can get better MPG that'd be great too. What are some of the pros and cons of each?

Here are a few of my problems:
I've heard the THM200 is garbage and not fuel efficient, therefore not worth replacing?
Would the 200r4 be a direct replacement with same cross member and linkage?
I've been told the 700r4 is my best option, but it's a lot more expensive and might require additional modifications to work (bell housing, drive shaft, etc.)
Shops have said there is a lot more work installing a turbo 350 such as custom mounting brackets
Can I keep my stock column shift with any of these without difficult modifications?
Is it difficult to install an over drive trans on a car not equipped for it?

Any input would be appreciated and thanks in advance.

 

[Evan11]

The 200 is basically junk, yes. A TH-350 trans is a direct replacement for the 200. 2004r is not a direct replacement. The shops are feeding you a line of sh*t about the 350 trans as they are a direct replacement. Fits right into the 200's place: same d shaft, x member, etc. only change u need is the kick down cable.

 

[G-Body_Vet]

It been some years since I've pulled a 200 metric but to add to what he ^^^ said I don't think the dipsticks interchange either. So if you go TH-350 get the dipstick and seal too.

A lot of us are partial to 200-4R's though. It's more work to swap but that would be the way to go for gas mileage. The good thing about 200-4R's is that our cars came factory equipped with them, therefore the parts to do a proper swap are there. You have a post '83 frame so you have the provision for the right cross member too.

I've never done a 700-r4/4L60 in a g-body so I can't speak on them as for the swap goes. The advantage of a 700-r4 is that it has a lower first gear, which helps if you have a crapping rear end gear. Downside is that there's more of a spread from 1st to 2nd gear.

Different builders will argue all day whether the 200-4R or 700-R4 are stronger too.

 

[gdouaire]

I had a 1973 olds cutlass with a TH350 and swapped it for a 200-4R. Best thing I ever did to that car - got stunning accelerations with a 3.42 diff and decent milleage and noise level on the highway.

I now have a 1984 Cutlass with a 200C and planning for another 200-4R swap. Moving the crossmember back to the second set of holes in the frame is the only major change I expect to do, along with the tricky TV cable adjustment.

 

[Stay Tuned….]

I am a fan of the 200-R4 I am going to be running one in my cutlass. If you decide to go with one, try to find one that was in a Grand National, if you can't, get either a hurst olds, 442, or Monty SS one, they have better valve bodies, and shift a bit better, as compared to one out of a caddy, or caprice. Good luck!!!

 

[Skitter302]

If you plan on a lot of Highway cruising get the 4th gear. It will require a bit more work but I would talk to gdouaire since he said he has done one.

If you don't want the 4th gear, I just did a P.O.S. th200 to Th350 swap and it was pretty easy.

You'll need a th350 Dipstick that can be found at any auto parts store. Th350 Torque converter. TH350 TV cable. The screw that holds in the TV cable. And you will need new tail housing bolts because those will be a different size then the th200.

Some cool things that you can do while the parts are out. Sand the rust off your drive line and paint it. Paint will keep road grime from building back up. I also cleaned a pained a bunch of the bolts that I had to remove. Made working with them easier.

 

[lilbowtie]

Don't know where you live but I have a bolt in 350 if you are interested ($100.00)

 

[NoRest92]

I had a 1973 olds cutlass with a TH350 and swapped it for a 200-4R. Best thing I ever did to that car - got stunning accelerations with a 3.42 diff and decent milleage and noise level on the highway.

I now have a 1984 Cutlass with a 200C and planning for another 200-4R swap. Moving the crossmember back to the second set of holes in the frame is the only major change I expect to do, along with the tricky TV cable adjustment.

Thanks for all the advice guys. I've narrowed it down to the the 200r4 or 700r4. I've read that the 200 has the same bell housing which is a plus since I won't need an adapter, but can I use the same drive shaft if I choose the 200r4? I'm still interested in the the 700 just because there seem to be a lot more parts out there for it. Can anyone tell me exactly what I would need to change if I switch to a 700r4? I am by no means a pro mechanic and am doing this off of a garage floor so any major mods might be a deal breaker.

 

[gdouaire]

200C driveshaft will fit with the 200-4R. All 200-4R have a "universal" bolt pattern that fits both Chevy and Buick-Oldsmobile-Pontiac engines.

In my case I will use also a B&M manual torque converter lockup, but you can run the transmission with the lockup unplugged also.

Not sure but a lot of 700's I have seen need an external computer.

 

[olds307 and 403]

The drive shaft is the same for a 2004R. I have used the same cross member between a TH250C and a TH2004R, just a different location. GM was pretty lame to keep the TH200C as long as they did, especially with the 2004R being better in nearly every way. It must have saved them 10 cents in production. The 700R4 is no prize but everyone builds them. You will need your drive shaft cut to run one.