I swapped my 10-bolt axles for 12-bolts in my 89 blazer. Now it is time to do the rear brakes, and I dont know what to tell the guys at the part house. I have no clue what the axles came out of. They have searched under early 80s c10 4x4 trucks, but no luck. I do have the stamped number (3989541), and the wheel cylinder I think is (519). How can I find the right parts?