I had a pile of Saginaw trannys.Some from the 70's. Everyone had the same diameter front bearing retainer, about 4-1/4 inches. Same as the hole in the older truck bellhousings,which are supposed to be the same from 48 on up.The bigger hole in the bellhousing applies to 68 and newer 4 spd trucks.I believe the trucks with 3 spd Saginaws still have the smaller opening.Looks like Bucks bellhousing may be the problem here.Perhaps GMC's are different, but a 235 housing will bolt up.
