UPDATE: Roger has supplied some additional photos and information to document the trailer in the hopes it will help others.
Roger writes, That is a light on the finder it as Griffin NO. 103 cast on it (10th photo). The light bulb is in side the cast aluminum tee . The jack as a PAT. NO. 2184058 The front panel of the box bed is 16” tall on the in side and 19” tall on the out side it goes down over the frame. The finders are 9” wide. The tale gate hinge pipe is 13/16 OD &14” on center & it well hinge from the top or bottom. The frame going up to the hitch is 3”x1 1/4”chanel. The springs are 1 3/4” wide. There are some holes on each side of box bed near the back that could of had tail lights mounted at one time.