i used 2" x 2" square tubing, cut the floorboards once tubing was welded to the sub frames I welded the floor boards to the tubing, it is super stiff. Intrusion into floor boards not a problem.
As I said the 8-1/4 is just fine. The rear end housing is out of an 80's Dippy with the diff out of an 80's van (in the van its called an 8-3/8). The reason for the dippy housing is it is 3" wider than the A body. I needed the extra width because I used 2003 Jeep liberty rims.
I installed a 2001 5.9l with a 92 518 od tranny in my 72.
I run 4:10 gears in an 8-1/4 with sure grip
Changed the computer and injectors to 95 and OBD1
Used a custom wiring interface from the Detail Zone.
Runs Extremely well.
Hi, I have a problem with no rear brakes on my 72 Swinger.
Technical
74 front spindle Actually replaced the whole K Member
76 Cordba 11-3/4" front disks and calipers
using a manual brake set up 2 bolt master cylinder from later model Mopar
New disk brake proportioning valve
81 dippy rear...