The U series (under Rockwell but were Timken) were made in both front loading and top loading designs. The ring and pinion (actually bevel gear) stays the same but the 1st stage reduction can be mounted out front or on top. My guess is that is what you have. The Timken design wasn't limited to what planetary gearset would fit inside a ring gear like the Eaton design so you could have wide ratio two speed with a Timken. It was that way until Eatons patent ran out.
Never had one or was around one however, they are mostly found in older stuff from the 40's and 50's.