70's and early 80's half ton chevies. If you want to go with chevy 56's I can hook you up, I have a chitloat of em. But I only have one set of 52's and I think I might have lost one of them at my shop.

52's are hypothetically better because of pinion drooping issues but I have been running 56's in Pigpen for the last 3 years and havent broken a single front driveshaft u-joint.