I ended up finding print copies of the Operator and Parts manuals on eBay. I don't have the time or resources to scan them, but figured I'd post some basic stuff here to help anyone searching for information.
These MC4000 units look quite a lot like the later Army MK4 units, which were also built by Case, but when you compare the parts manuals they are substantially different machines. They share the same Rockwell axles, but the MK4 has wheel brakes and the MC4000 does not.
General specs:
Engine: Detroit 5033-7098 (353 diesel)
Transmission: Allison TTB222-1
Torque converter: TT272
Axles: Rockwell D140, with No-Spin differential in front
Hydraulic pump: Cessna 24582LAC
Steering gear: Char-Lynn YP12-206-1131-001
Hydraulic control valve: Gresen 3283B
Filters:
Fuel primary: Detroit 1595655
Fuel secondary: Detroit 5578188
Oil: Detroit 5573014
Hydraulic: Case D43800
Transmission: Case A61234
Air: Case L33913
This is my new-to-me MC4000. It's had a lot of changes made, including a different (taller) mast.