What does the transmission look like? The tailshaft specifically? A few motorhomes had "normal" truck 727s with the HD tailshaft housing. The one where the access port for the retaining clip is on the side, rather than the bottom of the tailhousing casting. That housing won't fit in A bodies. The bigger Class A motorhomes have the parking brake (drum assembly) as part of the tail shaft. That whole mainshaft and tail housing is un-usable to you too.