I'd like to find out what it takes to swap in a 400 from a 700r4. Do i need a different cross member, and where do i get one? Can the original be modified? How much room is there in the tunnel ? And what to do for the torque arm mount? Will the stock shifter work even though now there's only three gears?

 

I'm trying to intall a th400 and I'm having the same problem, the cross member doesn't line up, so my plan is to get a large metalic beam cut it and drill holes in it and bolt it to the chassi, i tried a conversion kit and the mount for the arm is usefull, which you still need to modify it to get it to work, it's the crossmember where you get screwed over. I've got a b&m shifter with only three gears and it lined up fine, really didn't have any problems with it.

 

did you click search before you posted? i thougtht i'd seen soemone else ask this before, or tell how to do it.

 

I done the swap, and it's not hard, but the stock crossmember aint gonna work. The face to mount is close to 5" more to the rear on the th-400, so the crossmember will have to be offset. With these cars you can't redrill the frame and move the crossmember back like we use to do on the older cars.

I went with the best cheap swap kit I could find. It's the hurst swap kit, summit has it for around $125.
It comes with a new crossmember, a bracket to bolt to the trans to bolt the torque arm up too, vac line, shifter cable bracket, bolts, etc

There's more than enough room in the tunnel for the th-400, thar's not even close to a prob.

Here's some pics of mine.

http://community.webshots.com/photo/...27037846CBTFcr

http://community.webshots.com/photo/...27038781LewLMI

http://community.webshots.com/photo/...27039868lCGwPy

Also you'll need a shorter drive shaft. I used 1 from an 82-83 F body with a 200C 3 speed auto trans. It fits just right.

you'll need a th-400 trans slip yoke, conversion U joint to go from the F body drive shaft U joint size to the th-400 yoke U joint size. I got mine at auto zone.

Don't forget the th-400 and 700r4 uses a diff torque converter so you'll need a converter for a th-350/th-400

I can't tell you about the shifter, as I put a B&M pro stick in mine at the same time, but I would think the stock shifter would still work.. The letters for D, 2, 1 would be 1 off though I think. If I'm thinking right P, R, N will be the same, but OD will now be D, D will now be 2 and 2 will now be 1.

 

It's been a while since this thread was updated with new information.

I'm in the middle of a transmission dilemma and it looks like the TH400 crossmember may solve some of the issues.

https://www.thirdgen.org/forums/trans...v-case-no.html (700R4 "V" Case with NO TRANS MOUNTING HOLES.)

The Hurst and B&M crossmembers no longer have a presence on the internet. Meaning that they appear to be discontinued.
I've come across Spohn and UMI.

http://www.spohn.net/shop/Replacemen...GM-F-Body.html

http://umiperformance.com/catalog/in...roducts_id=300

I'm liking the UMI over the Spohn in that it looks like the UMI is adaptable to the factory style "clam shell" torque arm mount. Seeing as I have the UMI adjustable torque arm, it's a more economical route in that the purchase of another torque arm isn't required.

Are there any other swap products out there?