Just played this game with a 440 Sixpack install in my 1971 R/T Challenger.

First, you need to determine what size bellhousing you have, 10 1/2" or 11".

The tube length is 9", the difference in the torque shafts is how close the offset arm is welded to the end of the tube.
That determines what adjusting rod you use also.

E-body info at the bottom of the page.
http://www.brewersperformance.com/products.asp?cat=105