That is great that both motors are loose, maybe the one with the LaPlante-Choate hydraulic blade has narrow pads on it, yet it does look more on the 74" ga. side, the other one in the partial photos looks like it has wider pads. Just wondering, but more interesting is that you might get em both to run after some careful examination and repairs, also nice not to have to deal with unstucking the brakes and steering, they look like they've both been outside awhile. The hard luck is dealing with the undercarriage, might have to get real creative there, if the rails are'nt hammered, especially the bores and if they can be pinned/re-bushed, wonder if you can get something to cross reference to those pins/bushings, lot of work to pull the rollers, build those up, and not overheat them in the process, also build up the links, might be ble to take some slack out of them, get some adjustment back, pins to ride in the root of the sprocket tooth again, enough to keep the tracks on for light use, lots of work but could be worth doing seeing not many were built and it might run.
I would not know the differences on the air cleaner locations on these, that is for sure.
The LeTourneau PCU on there, have to wonder what model that is, am familiar with the later R7, biggest problem with those is the "driving" and "driven" cones, and getting the friction materials replaced on them, their manual does describe the re-lining process and removing glaze etc., they're dog bowl shaped, + all the bearing adjustments, clutch adjustment/brake adjustments etc., later caterpillar CCU's performed better no doubt, but the old LeT pcu's still do fine once you get everything adjusted, best to get the book for the model you have, they are not that complicated to work on either, as they are simple in design. I think a lot of the LeT dozer kits and other similar aftermarket equipment is becoming harder to find.
You should also be able to find the LaPlante-Choate technical manual, try e-bay, years back I found one for later D7's and in one instructional chapter on how to cut a side hill road is a reference photo of an older caterpillar Diesel Fifty with the same type of dozer kit as yours mounted to the track frame, except the blade looks to be an angle type blade. Both LeT and L-C, included operational instructions on how to take cuts, use the blade to push trees, grade etc., the kits they made for these tractors certainly laid the ground work for dozer applications, funny to read on how to use them in these books, was a new thing then.
I'm not sure, but I thought due to the scarcity of those manifolds, if this place might be able to help you on them, they do some interesting work on cast iron:
www.locknstitch.com/