I just rebuilt my box. The kit I got from one of the military suppliers was not correct. The input seals were too small, and the pitman arm seals failed instantly. I did some digging and found an old post on another site that stated his M1097 gearbox matched a 1979 Malibu 350, so I searched for a rebuild kit for that vehicle and they are readily available at almost all of the major auto parts stores. I listed what I found at O'reilly's below.
After finding out the input shaft seal that came with my military rebuild kit was too small, I picked up a new input shaft seal kit from NAPA using the chevy malibu information and those seals were correct. I put those seals in and reinstalled the rebuilt gearbox. Unfortunately, as soon as I cranked the motor, the pitman arm seals from the military supplier failed instantly, so I pulled the box again, went back and got a full rebuild kit using this same chevy malibu data and just redid both the input and the pitman arm seals, and everything was correct, and those seals have worked with no issues for a couple of months now.
I got my full rebuild kit from NAPA using the 1979 Chey Malibu information. They also list a rebuilt gearbox at O'Reilly's for $149.00, and it looks identical with the exception of the input shaft. The O'reilly's box has a small tit extending from that shaft, and mine did not have that piece. It might not matter that it is there, and it could probably even be cut off if someone wanted to try it out. I started to buy it, but was tired of fooling with this thing and just wanted to get the leaks fixed since my rebuilt box was working fine otherwise.
You can buy a full rebuild kit with bearings for $39.00 at O'Reilly's.
Precision Steering Gear Rebuild Kit - 28401227
Part #: 28401227 Line: PPS
or, you can buy just the seals and O-rings kit for $19.99.
Precision Power Steering Steering Gear Seal Kit - 28401226
Part #: 28401226 Line: PPS
I've had no more problems since using my NAPA rebuild kit and the auto parts kits are half the price of Ebay or the military supply guys.
If you are going to take the box out and tear it down, I would suggest you rebuild it. It's not that difficult as I am no mechanic really, and I did it. Watch a few of the videos first. then follow the steps in the TM Manual. Don't skimp though, watch a few videos all the way through. I watched several of them, as there are different ways to handle the small bearings. Below is the NAPA kit I used for $44.00. Maybe I just got a bad kit from the original supplier, but I would not risk it. Get a new kit from one of the auto store suppliers for half the cost.
Part #: NPS 7118
Line: NAPA Power Steering Parts
Update, some of the Saginaw boxes have a 7/8 input shaft, and I think the input shaft seals with the kits are for the smaller shaft, so you may need to add this kit to your purchase if you have the larger shaft. This kit will fit the larger shaft. Everything else matched up, just not the seal and dust cover for the input shaft.
Precision Steering Gear Input Shaft Seal Kit - 28401076
Part #: 28401076 Line: PPS