MEP-004A
Advantages: This machine has 1950-60 tech in it electrically. Simple, easy to fix and troubleshoot. The main gen is cast iron. The Engine is a runner. Rare that the engine is a total loss. Mostly, its all the little things thats going to fail, if at all. The MEP-004A and MEP-005A are the love of my life. If taken care of even a little bit, this set will run a LONG, LONG time. AND ITS SIMPLE.
Disadvantages: The set is getting long in the tooth. A few parts are tough to get. Having said that, If I were to get one, I would start in the rear, and move to the front. Inspecting and repairing as I went. Its mostly little things. I would upgrade lots of things, at a fairly low price, oil and fuel system for instance. The army built these things like a tank, and a few things could be done better. The electrical systems, well, the two of three biggest thorns in your side, A4, A5, have been re-manufactured by someone here in the forum. I would buy them and toss out the old ones, without even looking at them. That leaves the A11, static exciter. The card inside can be re-manufactured. The other parts, T1 and so forth can be found. So, for me, no real big show stoppers.
MEP-804A and MEP-804B
When these sets run right, they run great. Of the TQG gen sets, they are about the only ones I would buy. But the tech inside is much newer, and harder to repair and troubleshoot, for people who might not be "Mr. Good Wrench". The engine and main gen are tight in the box. Its harder to get inside to troubleshoot and repair. The main gens have had some problems, as Evvy can attest. Once the diode ring problem is "Corrected", the main gen is cast iron. The engines are fair to middle for maintenance and MTBF. But thew reason the B model came about was reliability, and parts. The Army had too many A model engine failures.
MEP-1050
There are some people that love this set. Its got a High Speed, Low Drag computer in it! Well, the High Speed, Low Drag computer works well, till it dont work. Then you have problems. Parts availability is very bad. Cost, if you can find one, is HIGH. The set has TOOOOOOOO much high tech. Hard to fix or troubleshoot. If you do not read the books, you are lost. And in comparison to the MEP-804A or B sets, there is room to play foot ball in the box. Ten pounds of crap, in a five pound bag. Very sensitive to low batteries. The military is having a hard time supporting these "computer" gen sets. The just retired Master Tech, of CECOM, Communication & Electric Command, once told me, "Guy, if you ever buy one of these things, I will personally get in my car, drive to where you are at, and beat you with a Baseball bat, until you are nothing but a red wet spot in the mud." I suppose you could say I don't like them.