Yours is in very good internal condition. Some years ago I took two D2N winches and made one. Had them both totally apart as you have. Not rocket science. Very well built and easy to work on. I like equipment like that. One of the two had been worked so hard that the input shaft was twisted and one gear was broken internally.
All of the bearings are pretty much standard stuff you can buy aftermarket. Just cross the number on the bearing case. I replaced the input shaft bearing with new when I did mine. I think one other bearing went back new, but most I reused since I just picked the best of the two old bearings. My winches don't see tons of use so they will outlast me easily.
A negative with these winches I feel is there is no disconnect clutch from the main transmission. You can choke out the diesel if pulling hard enough. Been there, done that. And I find it very hard to wind the cable back in neatly. I usually hook to a tree and drag the machine back, touching each brake to try to reel the cable nice, but it is very hard to see the cable reel when seated. You have to lean way back over, then it is hard to work all the controls. It is nice having the winch. I've pulled a friends F250 king cab diesel out of some muddy soup. Pulled over some trees and once got my backhoe so stuck I didn't think it was ever coming out. Chained the D2 to a tree and a friend pulled the backhoe while I worked the buckets and it finally came out.