Hi Anthony
I would not give up on this box, rust on gears often looks far worse than it is. Two of my CMPs had transmissions as bad or worse than this, and they both clean up and have many thousands of miles on them after going back on the road.
I started by removing the bearings then polishing each gear tooth with 3M rowloc pads, used old wheels with most of the abrasive worn off, with a very light touch, object remove and smooth the surface. I didn't try polish out the pits, leave the pits alone.
Take a look at the photos
http://canadianmilitarypattern.com/C...ansmission.htm it shows, primarily, the transmission in my C60S as I started 1990 and then 2008 and 12000 miles later. When the main shaft got noisy and had to be replaced, new shaft and it ran for another 10,000 miles before breaking a tooth.
http://canadianmilitarypattern.com/3...ansmission.htm
That time I got lucky and found a NOS gear box, can we say scarce as hens teeth. Yes, I did find a replacement gear and rebuilt the first transmission, which with three CMPs on the road sits on the shelf full of gear lube ready to go in.
Back to my point, if the gears and bearings areas clean up it will probably give many thousands of miles.
Keep us posted on your progress.
Cheers Phil
PS I'll look to see which of my photos need to be moved to MLU.