The hubs for 73 to 77 1/2 are not the same as late 77 to 87. The dimensions and bearings are different. I learned the hard way because i bought parts for an 86 k10 and they didnt fit right. Then i got the numbers off the frame and its a 77. 73 to the first half of 77 is different then the second half of 77 to 87.
I havent seen one piece rotor and hubs anywhere. I can get rotors for a 2 piece setup but ive only found one place that has hubs available and theyre used and 200$ each. I cant be the only one to run into this problem