measure the housing from flange to flange(where the backing plate bolts to housing)

whats the wheel bolt pattern? 5 on 4 1/2"? 5 on 5 1/2"?

look along the bottom of the pinion and get the last 3 didgets of the casting # to tell what chunk you have...741-742-489

if you pull the chunk it will have the yr and gear ratio on the edge of ring gear

measure the spring perches center to center for a better guess of what it ut of

all the gaskets and wheel bearings are the same for a stock 8 3/4 unless it has green roller bearings put on it at some time

the only seal that may change is the pinion seal..depends on the chunk you have as to pinion size

the chunks swap a round expet for the real older ones and matching the carrier to the correct case bearings ect..

that will get you started on IDing it

post the measurement and #s for a better guess

dont forget to sand blast and paint it