I don't own a CJ-3A so if I'm wanting to research specifics, I'd search using the 3A jeep icon above as a starting point. You can also do a dive into the "3A Projects" section in this forum and it may help alot. I also own a copy of Bob Westerman's book,
The Civilian Jeep Model CJ-3A, also a great reference.
One link on the 3A Page I visit from time to time is:
https://www.cj3apage.com/index/My_1950.htmThere's detailed images of various components. Components that look different from the images you shared above. For instance, I also wonder about the hat channel brace under the right fender - it's different from what I am used to seeing on a civilian jeep. Plus, the hat channels running under the floor are laid out in a way that is unusual to me. The rear axle appears to be a later D44 (again, don't know if 3A's switched from D41 to 44 at some point). I would also expect to see the "WILLYS" stamp on the tailgate of a 3A.
I see images of more than one frame, so I don't know if it's just random images of multiple frames or all the donors used to cobble together what is now under the jeep. There is a good reference on frames here:
https://cj3b.info/Dating/DatingFrames.htmlYou may also want to reference the Serial Data Plate on the firewall to see what it says, as well as the engine Serial number on the flat boss above the water pump. That would help too.
I know that things were constantly changing during the production run of these jeeps. Knowing what year that jeep is supposed to be may help.
Also, I've read threads before about, "which part makes a jeep that model jeep?" e.g. Is a 3A with a rotted frame using a swapped in (modified) 2A frame still a 3A? Is a complete 3A (frame/drive train) with no body using a 2A body (complete with Serial Plates for registration) a 2A or 3A? etc.
This could get deep. From a distance, that jeep looks like a military jeep. I can see non- civilian items, but modification is easy.
Here's a question. If it really is a CJ--3A and those are rare, wouldn't it maybe make more sense to restore that vs. modify it to resemble a military jeep? What is the seller saying?