Does this work?
https://www.stockwiseauto.com/centri...xoCwFwQAvD_BwE
Or try LMC part # 34-3960, Rear Brake Drum, 4 Wheel Drive 3/4 Ton 60-66
And since you have a K20 here's a guy that might help with other parts -
https://torqueking.com/category/1960...series-trucks/