Right, I looked at a Spen for comparison as well and its definitely not that. It does seem to be similar green to David Bradley, but Im not convinced. What do the wheels look like under the hubcaps? any square holes that could be used to mount wheel weights (on a tractor)? Thats usually a good sign of a DB or similar brand that manufactured other equipment.
I believe the wheels are late 40s to early 50s Mopar. I have a 45K mile original '52 Dodge truck in the garage with confirmed OEM wheels and what's on the trailer is identical, down to the hub cap clips. The green paint under the hub caps and body is your typical post war implement dark green gloss like Bantam trailers or maybe Oliver tractors wore back then. I can't bring myself to deviate from green, so I am planning to paint it a vintage Coleman lantern color.
There are a few photos floating around the web of trailers with a tub like mine, but set up for dump rather than fixed tongue. This might have been the "cheap" one as no dump capability and 2K axle. It obviously had the leaf springs changed at some point as you can see where the rear hanger was moved aft. From the existing original measurements I am pretty sure it came with Jeep CJ2A type front springs. Dump feature and leftover military influence (fenders, springs, axle placement, dimensions) makes me think Converto, but that's just a guess. That being said, it has a square axle, unit body construction and is bolted together, all like a Bradley, so who really knows?
This probably isn't some ultra-rare collector item, but I am still going to refrain from butchering it up since the cool factor is strong with this one. Unfortunately the tongue is both bent and farmer welded so it is not salvageable. Other than that it will remain basically stock looking when I'm done.
Thanks for your interest, it's great to know there are so many other vintage trailer nerds out there...