I have never measured them, just going by what the pictures say. All of the Mopars I have crawled under had the transmission mounted at the torsion bar crossmember, and given the fact that the b & e torsion bars are 5.3" longer than the a-bodies things have to be different. I need to check the web site where I got the Challenger pictures. Pretty sure there is one of the bellhousing/firewall relationship. On the CHallenger picture, if I remeber right, the top 2 bolts are very accessible, on my car clearance holes were needed as the top 2 bolts are right against the firewall.....