D8 2U with water/ice in transmission

I bought a D82U last winter. This Cat had sat for 15 to 20 years before the previous owner had started it again to sell. It was a warm day when I started and loaded it. A few days later when it was much colder I started it to move it by the shop to work on it. The Cat would not move. This spring I drained the tranny and a large amount of water came out. Over 5 gallons I would guess. Now I have time to work on it again, is it likely that anything is broke? Especially wondering about the tranny lube system as I did have the clutch engaged with the tranny in neutral. Can I check this by leaving the filter off to see if there is good flow of grease to the filter housing? I don't know about the internal workings, and I don't want to cause further preventable damage. Thanks

Normally an accumulation of water drained before start up is not an issue. The oil clutch and transmission circulating pumps are mounted high enough to where static level normally wouldn't reach them. Yours appears to of had have enough to freeze and prevent the transmission from turning. Biggest problem is if the unit was started and run, circulating water throughout the transmission. No telling what damage may have been done. I suppose cracking a line or opening the filter would give some indication but sure going to be messy. Thought you might be able to put a pressure gauge on the system but darned if I could find a place to tap the gauge and although the pump has a relief valve I couldn't find any spec for its pressure rating.