as long as you dont see any water in the oil. . .or a milky look to the oil your fine.

 

Concerning your differentials.....
I got a 4 wheeler from a freind of mine a few years ago. He didnt want it because the front end bearings were shot (wheels would wiggle back and forth a good 1.5" each way). When I pulled it all down I found the axle tube had water and was rusty as hell. I pulled the differntial apart and everything looked new despite the water. Point is that everything is coated in oil, drain it, refill it and your should be ok. Get those seals done asap though.