Ummmmm NO.....
Crew Cabs were only F-350's pre 1997.... (Ford did make a Crew Cab short bed F-250 SWR in 1997) and the 99+ SuperDuty's do....
Dually's were only F-350's also.... and if it left the factory with a pickup bed, and was a Crew Cab Dually, it was 2 wheel drive..... Ford did not produce a 4x4 Crew Cab Dually with a pickup bed before 1999. They made 4x4 dually's and they made 4x4 crew cabs with a pickup bed, but they were ONLY SWR.......
My thought is someone changed the badges on a dually (or fenders that had badges)..... but it wouldn't be a half ton crew cab in the early 80's..... the F-150 didn't get 4 doors until the SuperCrew in the 2000's......
Also, wouldn't be a 429..... they put the 300 inch 6, the 302, 351 and 460 V8 gassers in them..... (or in 85 it could have had a 6.9 IDI) 429 had been discontinued, and I don't think it would be a serpentine belt either.... we had an 83 F-150 and a 85 E-150 and they were both V-Belts and carb'ed. This one is serpentine and EFI....
It is a factory Non-A/C truck.... no dash vents..... and this engine has a serpentine A/C idler that replaces the compressor, and the V-Belt trucks, just didn't a compressor and belt.....
I think this thing is a mashup of many different things......
Also, not pertaining to this truck, but Ford, to this date, has not put a diesel in a half-ton from the factory. All Ford Diesel Pickups have been 8 or 10 lug...... if there is a diesel in a half-ton or Bronco, it's not factory...........