Going to change trans from short th 350 to short th 400. How much shall i shorten the driveshaft? 11/16"? Some who has done this swap and remember how much they shortened the driveshaft.

Thanks

Marcus

Transmissions are 11/16's difference so Yes,11/16".
http://www.tciauto.com/Products/TechInfo/trans_dims.asp

You also have to take into account yoke differences.
The best bet is to install the yoke, bottom it out, pul it towards the rear 3/4" to 1", and then measure center to center. Be sure the car is level and suspension loaded.

Just using the difference in trans length will get you into trouble, especially on this swap. You are making a lot of assumptions.
Same length yoke, driveshaft was correct to begin with, etc.

You also have to take into account yoke differences.
The best bet is to install the yoke, bottom it out, pul it towards the rear 3/4" to 1", and then measure center to center. Be sure the car is level and suspension loaded.

Just using the difference in trans length will get you into trouble, especially on this swap. You are making a lot of assumptions.
Same length yoke, driveshaft was correct to begin with, etc.

Ok jake will follow your advice.

Thanks

Marcus