M561 Gama Goat with RTT in MASSTER

My next project in the series of vehicle builds from the 1st Bn, 2nd FA, in MASSTER will be and M561 Gama Goat, with an S-250 shelter containing an AN/GRC-122 Radio TeleType (RTT) rig, pulling an M101 3/4 ton trailer with a 3 KW Generator.

I’ll use this post as a build log, and then when finished post the completed project pictures both here and in my over all Battalion posting covering the entire unit.

I am going to us the TAMIYA M-561 this time and the Plus Model SC-250 resin container, along with the MinimanFactory M101 3/4 ton trailer.

I have already done some work on this one, including scratch building a 3KW generator. I had already build one for the FADAC in the M577 FDC track, so I simply copied what I had done. Technically BOTH vehicles would have TWO of these, one running and one spare, but I’m only going to have one with each vehicle.

And I have also done a bit of work with the shelter. The kit instructions show the PE racks on either side, but all the photos clearly indicate that rack is in the front of the shelter, so that’s where it goes. This also allowed me to be able to have a predetermined space into which the individual components needed to fit.

My son and I (my direction, his work!) created several CAD models and used a 3D laser printer to create most of the necessary components. The ones that we didn’t create I will just go old school and scratch from styrene.


Oh boy! I’m well acquainted with the S250 shelter, but carried on the Gama Goat replacement, the M1037 HMMWV. Of course we had a completely different set up inside for our needs. But yes, the racks could be configured on a side or at the end opposite the door, depending on the equipment to be installed.

All of the references and TMs I found were from the earlier set ups and show the equipment on the front wall. I know that our rigs had two antennas, so based on that, I’ve GUESSED at what equipment they had inside as I never actually got a chance to see inside one.

But the -122 seems to fit the bill based on the time frame and so I’m going with a “Duplex” configuration which seems to be consistent with needing two antennas.

No worries on that. Up front is more common in the ones that I’ve seen. But I’m sure that the commo gear in ours were different due to mission needs. The basic shelter is an empty box, then equipped & arranged according to unit TO&E and SOPs.

I’m figuring that given this was back in the early 70’s the gear probably all had TUBES!!!

Lol! More than likely…

As I usually do when I’m building a vehicle and a trailer, I’m starting with the trailer first, for the most part. I’m using the Miniman Factory M101 which is a very nice kit, but I’m making some modifications and using some parts from the old Italeri trailer kit because I found the last time I did an M561 and trailer those parts worked better.

First step is to drill out the hinges on the tailgate. I drill those out with a 0.020" index bit and will probably use that diameter styrene rod for the hinge pins. There are some very nice PE hinge brackets with this kit so I won’t have to scratch those.

Next I’ll replace the kit’s solid resin axle with a scratch built one which is made from a styrene tube and a smaller diameter rod, which will allow the wheels to turn.

To get the resin wheels to fit inside the tires, the inner diameter needs to be sanded open somewhat and the inside surface of the wheels also needs to be sanded out so that they will spin on the wheel end/brake assembly.

Here’s the front end of the trailer with the Italeri “A” arms and lunette as well. The support stand is scratch built as is the hinge box. It’s designed so that a pin, attached to the front of the hinge box with a piece of thread can insert in one hole when the stand is down, and then pulled, the stand rotated to the rear, placing the pin back into another hole to keep it in place in the raised position.

And while I’m working on this end of the trailer, I’ll go ahead and open up the tow pintle on the back of the truck, and remove the cover for the electrical socket, drill out a hole for the plug, and then glue the cover in the raised position.


Great work so far

You had to be there!

Yeah, they were a piece of work. Or something…

Ain’t that true!

Excellent subject and start to the project. My lovely bride was an Radio Teletype Operator at Ft. Hood in the mid 70’s. I need to build a RAT rig for her.

Well you’re in luck! I have extra components made up for a lot of the stuff! The transmitter/amp/modem units etc, I just made front face panels which will easily glue onto styrene to create the whole unit. And they are all on shelves anyway. But we did create full 3-D models of a couple of the teletype machines.

I’ll post some photos with nomenclature later. You can tell me what you need and I’ll be happy to send them to you since I had extras.


Another fantastic project! This one has something of a connection to my dad. He worked on the previous generation of RATTs in the mid 50’s in a Nike-Hercules unit at Ft. Niagra when he was in the Army. Bit of trivia for you - the founding members of the band Ratt served in 7th Signal Battalion at Ft. Ord, CA; the name of the band comes from their MOS, at least one of them worked on the RATT Rig.

That’s a really neat piece of trivia for sure!! I remember visiting a Nike site in the 50’s when I was about 7-8 years old. They let me go inside the fire control center and look at all the stuff figuring that I probably wasn’t a security threat! Hard to imagine now how we had all those missile sites all over the place back then…

Today was an easy day. I scratch built the stake sides and the gate for the trailer. As nice as this kit is, it’s a bit surprising they didn’t include those, but in any event they’re easy to do, and besides, when I’m done, they’ll be covered by the canvas tarp.

Next step is a bit more work: making the hinges and the latch mechanism for the gate. Luckily since I’ve already built one M101, I don’t have to “design” it, all I have to do is copy what I came up with before.


Today I finished the hinges and latch for both the upper “gate” as well as the tail gate. I’ll use the pin in the upper gate as the latch, securing it to the gate with a string. The tail gate hinges are temporary, and will be replaced with a separate bent piece of wire in each one. The kit also comes with a latch which I’ll add later and secure that to the trailer bed with a chain. I’m always glad to get this part of the construction done!!!


Your “gen sets” are amazing. I can see them on any number of different builds. As for the Goat, well they are just a bit quirky IMHO. The local NG Unit had them for a while, always loved watching the drive around in parades and such. Eager to see you radios as most kits have pretty basic bits. Perhaps you & your son could laser print modern comm gear including cables, antenna couplers and such? I LOVE your project & all its subtle details!

Thanks so much!! I might consider the antenna couplers, but generally they are probably just as easy to simply scratch build. This build will require some for the antennas and I’ll decide on how to do those once I get that far.

And as far as the cables, I generally just use regular black thread, run through a block of bee’s wax (for stiffness and to coat it) if I’m going to show wires. And for mic cables I’ll just use thin wire wrapped tightly around a thin rod and then stretch it out a bit.

Yeah the Goat was definitely something where the idea turned out to be much better than the actual execution! The same can probably be said for the GOER as well. I’ve said it before, but I can distinctly remember the conversation I had with our Battalion Ammo officer when they replaced all of our 5-Ton M54 ammo trucks with the 8-ton GOERs. The planning weenies who designed the TO&E decided that since two 8-Ton GOERS allowed for 16 Tons of ammo where the three 5-Tons only had the capacity for 15, that our battery level TOE could be modified from 3 trucks to 2. (And the 9 vehicle/45 Ton Capacity Service Battery section was replaced with a 6 vehicle/48 Ton Capacity section.)

The PROBLEM was that even though the capacity by WEIGHT was greater, the actual usable cubic feet of SPACE in which ammo could be stored was just about the same as the old 5 Tons, meaning that instead of increasing our hauling ability, it had been cut by about 1/3. Genius!!!

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The good idea fairy strikes again!


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