Rear End

do yourself a big favour and pull the differential confirm the gear ratio and whether you have a sure grip or not and have it rebuilt as long as the gear set look good , its a 50 year old part along with the gear lube and axle bearings . clean the inside of the housing and reinstall the new parts . why do people do this , spend x amount of $$$$ on the engine and transmission not counting what $$$ spent on the body then want a 50 year old differential to push the car down the road ,, it will let you down when you are the farthest away from home and when you least expect it . rebuild it now and save yourself the grief .