Yep, It's a Sag.
I don't know what it was originally out of but a truck I suspect since it is a 5 bolt housing.
It was being used as part of a horse exercise carousel, and yes, at some point in it's life, it was under water, tho not during Harvey. Belongs to a friend of mine and I told him I'd look at it. It was seized up, but for what it does, I think I can get it going again after I change the front main shaft bearing. The outer race is cracked. (see the white arrow in the photo)
I've already powerwashed the inside, and it looks surprisingly good and shifts thru all the gears fine, tho in operation, it wouldn't have to since it would stay in low gear all the time...maybe reverse or neutral occasionally. The electric motor is new and runs at 1800rpm, but the belt pulley reduction between the motor and transmission looks to be about 10:1..further reduction will come from using 1st gear and another reduction using small pulley on tail shaft end of the transmission shaft and another big pulley on the input of the differential.
A home built job, going by the welds and and torch cut shaft ends. Would have really helped me, if they hadn't welded the big pulleys to the input and output shafts of the transmission.
Still, I gotta hand it to someone using junk parts to build something that works.
Pardon my crude drawing, but it's basically set up like this:
Not the only one either it seems.
http://justacarguy.blogspot.com/2017/03/home-built-horse-walker.html
I am curious what they did to the inside of the differential, as they had to find a way to lock the bottom axle on the bottom because, if it wasn't driving anything, the top one wouldn't spin unless it is a posi-trac, and judging from the age, I don't think it is. The whole bottom end is just torch cut off about 1 foot down from the chunk, so I can't see what was actually done with it.