What will I need to swap out or change besides the torque converter? Driveshaft need to be shortened? I am running a spohn torque arm for a 700r4, will I need to buy a new one? Just looking to see what is involved when swapping these transmissions. Thanks.

why would you go from a 4L60 to a 4L40 ???
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i believe they are the same length find one in a salvage yard and measure them

700r4 I have now didn't even last 3 weeks it was mildly built. I thought about rebuilding it stronger but everyone I talk to says that a 200r4 would be better with my setup and would last a lot longer. Check link in sig to see what my current setup is.

I assume you have 200 out of a GN? If not you will need to get one. The GN 200 is a unique beast. Definitely not you're average bear. I think the two are the same length, should be able to use the tail housing from your 700 to get the tourque arm mounted. If you don't run a GN 200 it won't last as long as the 700 did.

They are not the same length and the tail housing does not bolt on.
They can be built to be like a TTA trans or GN.
You will need a different crossmember, torque arm and driveshaft.
Not sure how you will run the speedo, yours is electronic.

Hmmm....

Maybe I won't be switching to a 200r4 then....

2004r is th350 6" tail length

same as 200c and th250 and so on




need longer driveshaft by 3"

200C driveshaft that is

we have a 2004r in the 85 elky ss

i have had a few 2004r over the years

pretty good tranny

the big block olds guys run them behind their really strong modified engines all the time no problem



good luck

700R can last plenty long. If you blew yours up, either it did not have strong enough parts in it, or it wasn't built properly. It was one or the other.

Guess we will find out. Going to try the 700r4 again but built a lot stronger and by a different company.

This is w/ the 6'er in front of it? Let us know how it goes. Did you use an aftermarket sun shell?

Yes, with the GN motor and no I didn't.

The last HD sun shell I bought was about 80 bucks, and that was 3 years ago. You can also modify a TH350 piece to work. I don't have that book anymore, so I don't have instructions for you.

I like the gearing in the 2004R better, so that's my choice. The GN guys like 'em, and the TTA survived with one, so...

It's just my opinion.

I want to go with one too. But it will cost me a lot of money since I have to modify the driveshaft, buy a crossmember to get the torque arm to work, and TC + the rebuild. Rather just have the rebuild cost.

I understand...

I guess you should start collecting parts little by little for next time!!

I think you should get a used crossmember from the wrecking yard, make it look like this picture with a welding machine, and make it work.

You can get 2004Rs reasonably enough. There was a GN unit on eBay for 100 bucks in Oklahoma not too long ago.

If I were you I would go for a TH350 instead of the POS TH200,Which has crappy stamped steel internals.

That's what I had in my 82 T/A and it only had 70K miles when I did the swap/rebuild.Best $500 I ever spent


Dave

What are you talking about? Nobody wants to run a 200!

A 2004R is a totally different animal. You can swap the torque converter, I think...

A few things here...

2004R has two different bellhousing patterns, B-O-P only, and Chevy/BOP multi-bolt pattern. The BOP only ones tend to be the early models 82-84ish. Most 85-90 are multi-bolt pattern.

The tailshaft is not removable. If you search this website you will find the pics of the underneath of a 20th Anniversary Trans Am with the 3.8 Buick Turbo engine. It runs the 2004R trans because that's what the Buick Grand National ran. The engine (minus the cylinder heads), trans, ECM all came from the Grand National parts bin.

There was a custom, one off set of engine mounts, and a one-off trans crossmember used. This crossmember has the torque arm mounted to it instead of having the torque arm mounted to the transmission. You will have serious trouble finding this part, but SPOHN and others sell the proper crossmember for you to run it with a separate torque arm.

The driveshaft is a different length. You will need either an 89 TTA driveshaft, or an 82-83 driveshaft from a car with the 3 speed auto, which would have been the TH200C.

The TH200C has the trans mount in a different location than the other transmissions, so it won't help you put a 2004R in. The 700R4 crossmember is close, but you will need to put in a provision to mount the torque arm away from the trans and maybe slot the bottom to let your trans mount bolt up. I will be working on this soon.

Good luck guys!!