Look in your want ads and any classified ads like "Buy/Sell Bulletin" or "The Swapper" are what we have in Alabama. You'll almost surely be able to find an old chevy K20 with the set up that is a perfect swap for your M1009. I found a 1978 K20 with no engine or transmission and missing doors with a whole bunch of rust for $175. I towed it home on my trailer, took the axles annd springs out, scrapped the rest, and ended up paying about $100 for everything I needed for my now-true 3/4-ton M1009. It even had 3:73 gears, which are perfect for the 36" tires I am running with the TH400 trans.
Incidently, it might help you to know in late 1977 is when GM began manufacturing their own, hence corporate-design, axles. So if you get 1978 or later, you will have a thicker axle tube in the front end.