You have a 30 spline. Unless you have an old 557 center section out of an old " Copar Panzer " or " Pennsylvania Panzer " tractor. Yes that is what they came with a narrowed 8 3/4 rear with 557 gear set. They also had Mopar brakes shoes and drums.
Also green bearings take no side load they are for straight line racing. Or mild tempered street driving.