Found a GMC DUKW when I stumbled upon our local military museum. The museum itself has no info on the vehicle or where it might have come from. Taking a closer peak I found a serial tag, date of manufacture, and the factory it was produced in. The vehicle isn't in great shape as I'm assuming it's been sitting for at least 20-30 years. But its been completely untouched, the motor and original wiring are still there, the air lines for tire pressure system are still there, even the Jerry cans are still attached although I'm not sure they are the original ones.
Mostly I'm looking for places to find more info for this vehicle. I'm interested in it's unit and where it served. The original stamped plate is still attached to the bulkhead so I was able to gather some details and the serial number on the side matched that plate.
General Motors Truck
Amphibian Truck 2 1/2 ton (unclear) Supply Service Maintaining Vehicle Ordinance Department
GMC DUKW 353
Serial Number: 353 11203
Date of Delivery: 07-44
I suspect your best bet would be to check in with the Military Vehicle Preservation Association. They have chapters all over the country and there will be some other Duck owners in the group. I would not be surprised to discover that they can find, or at least direct you to, the answer to the service question.