What we have here is a conglomeration of a lot of different Jeeps. The front axle is from an MB, or WWII Jeep due to the steering bell crank being mounted to the axle. The frame looks to be a CJ 3A 4X4, with how the front frame horns step up on the top frame, and the lack of crossmember brackets. You are correct that the military frames did have the provision for a machine gun mount, to which your frame does not have, (it would have been welded onto the most forward rear crossmember to be placed in the center of the rear cargo floor. The top is an option, (dealer installed) but the rocker panels being cut on your DJ body was done after purchase, or so I thought. The last link at the bottom shoes what appears to be a factory DJ with the same door modifications that look original. Another feature that says that your tub is a DJ is the round speedometer with integrated oil and water gages.
The photos are 1) An M38A1 frame with the squared machine gun mount affixed to the crossmember. The earlier ones were round. 2) This is an late CJ2A or early CJ3A frame that has the engine mounts directly across from one another. 3) another shot of the previously mentioned frame, just more of the rear hitch. 4) This is an M38 frame that had the machine gun mount removed before I purchased it.
DJ example links;
http://www.ewillys.com/2022/06/23/19...anson-mo-3500/
http://www.ewillys.com/2018/06/19/19...unty-ca-12500/
http://www.ewillys.com/2010/06/08/19...rings-wv-ebay/