V8s said 'total width' (WMS?) and Fillpot said flange to flange? 54.5" total width worked w my 69 w 12" wide rears on a 5.4 BS. On my Ford 9/Moser that made my flange to flange total width 50.5 (+2 on each side for the axles)....
Also consider panhard bar (or lack of) and sidewall flex. Also Wiwood rotors push you out another .25" I believe..
