[GMCPaul]

All 1969 were originally drum brake front and rear so someone's converted it to disc brake front. When converting it they've either used aftermarket spindles, or stock 71-72 spindles, or stock 73-87 spindles. No matter what spindle year group they used they all use the same brake pads as 1971-87 brake pads are the same for all 1/2tons with 1 1/4" thick rotors or 1" thick rotor.
1973-80 trucks all used 1 1/4" thick rotors & 1981-87 1/2tons could be either 1 1/4" thick or 1" thick rotors as in 1981 they began offering light duty rotors that were 1" thick. But the brake pad used is still the same.
So buy any front brake pad for any 1/2 ton 2 wheel drive from 1971-87 and you will have the correct brake pads.
If you see a part # that is numbers only on the spindles its GM, if you see a part # on spindles that's letters & numbers its aftermarket conversion spindles.
I believe I covered all your questions so time to get packaging todays out going orders.
Paul Jr @ GMCPauls