Yes that would be the maintenance truck that had all the tires and other stuff. They were M54s by the time they had maintenance trucks if I am not mistaken. It was a process of figuring it all out as they went along as the Army looked the other way. It's not accurate but gives you an idea of what a gun truck was like without spending $150 for a real model conversion.
I plan on using some stuff from it and just making my own version of a M35 gun truck model.
I really think the only way to go if you want the real thing is to order the real thing or as close as you can get.
I spent a lot of money and have a whole series of gun trucks and jeeps planned. But it was costly. The amount of different models was mind boggling. So many had different versions of themselves, they changed names, paint jobs, armament and with rotations and KIAs the crews would change and they would change things too.
The ones you see a lot of were just a few of the many. You can conjure up some version in your head and I bet they at one time tried it. I love the M54s with the M113 hulls on the back. One had it facing backward. They were not successful. The most successful were probably the ones with a mix of 50cals and M60s. Mini guns were great but required a lot of maintenance by trained personnel and they ate tons of ammo. But honestly what is cooler then a mini-gun? If you do a version in a fire fight you could put a big blast of flame out the front........I think that's an idea.
One jeep that i thought was really cool was a M151A1 with a ring mount from either a M548 or M35 and a 50 cal. I saw one like that and never saw another. Like the one with a triple 60 mount. The more you dig the more stuff you find. I am still looking for the M48A3 with the minigun at the loaders position called "The Grim Reaper".
I am surprised nobody ever mounted a M40A1 RR on the top, that would have given them a lot of firepower and there were many in country.
They did also use a few M37 trucks for the officer of the convoy. I am going to attempt to a conversion of one of the WWII WC whatever and scratch build it. It doesn't look too hard, they were very similar. The biggest change was the front fenders and the cab in back. But the cab is squared off without major curves which add to the complexity.
I find the ones painted a normal OD Green much better to myself then the garish semi gloss black ones with the yellow noses. Maybe I'll build a few like that but I can see it being much harder to make it NOT look like a toy made of plastic. I guess that's were the real skills come in. I'm thinking oil paints are a must for that version.
If you read about their exploits you'll find the men who served on the Gun trucks to be courage men who were a special breed. They were elite in their own right.