The reason the part number is different is because the hp24 used behind the 4.0/4.6 takes a totally different torque converter from the hp22. The crank adapter, spacer, flywheel/flexplate are all different between the two trannies, but the 6-bolt crankshaft pattern is still the same, just that the bolts are not evenly spaced. I've done several 4.6 swaps into RRCs so I know this firsthand.
1991 RRC 4.2, R380, LT230, TrueTrac, Detroit, sliders, 33s, blahblahblah....
1994 RRC LWB
1994 RRC SWB
1995 RRC LWB 25th Anniversary Edition
1995 D90 project