As far as I know, all M1028A1's, A2's, and A3's were conversions. An M1028A3 would have been a converted M1028 (which the 5077 NSN confirms). The M1028A2 is a converted M1028A1. And, the M1028A1's were converted M1031's. They should all have an MWO plate stating they were converted into whatever, as well as a Mfr. plate on the drivers door jamb with the original NSN (either M1028 or M1031).
I have heard that a few duallys were factory built, but I don't believe they were actual M1028A2's or A3's. I have seen a number of dually M1028's with communication boxes on the back, that appear to have been factory built. These were all also 1987 models with the 200-amp charging system.
I'm not convinced any were deliverd with pickup boxes, since the NSN's for the dually versions are so far after the rest of the series. The truck in my avatar (also M1028A3) was converted by me with an original kit, so I am fairly intimate with every part used. It had the following:
- Fenders and all other GM dually parts, the fiberglass parts and other metal panels
Data plates
Front hubs and seals
Dana 70HD axle
New driveshaft
New proportioning valve
Rear swaybar kit (new perches, u-bolts, end links and frame brackets)
New side mirrors
Wheels, wheel lug rings, rear spacers for between the wheels, lug nuts, screw-in valve stems
A template for cutting the bed in the right spot for the conversion.
And... all necessary hardware (right down to rivets for the data plates).
They must have only had access to a partial kit when they did this truck. Attached is a pic of the data plate they would have used if they had a complete kit. Unfortunately, I don't have a pic of an M1028A3 MWO plate, although I do have one somewhere of an M1028A2 MWO plate (which has an incorrect NSN, too!
)
Also attached a pic of the crate with the fenders from my kit...
Technically, only the M1028 and M1028A1 were "donors" for the conversion. But, as I said, I have seen converted M1008's come out also...