After months of searching and having 3 different ones sold before I could get to them... I finally found a very clean M416 here in Fort Worth.
I got it from the original owner who bought it from the DRMO auction and it's been stored inside since 1991.
Everything works including the parking brake and it's all original.
It's so clean, part of me wants to leave it as is.. and the other half wants to tear it apart and rebuild it.
I'm planning to leave the tub watertight but having bedliner sprayed after I do a complete frame off resto/Por15 and paint treatment.
Possibly looking into doing a spring over conversion with a new 3500 axle with the same 5x4.5 bolt pattern so I can run the same wheel/tire combo. Only draw back will be losing the working emergency brake.
I found a wiring harness on ebay for an easy 12v and maybe led upgrade.