Pointers for replacing prop shaft and drive shaft seals

Okay, finally getting the bugs worked out of this motor. I realized that I changed the impeller in the old lower unit, but I switched due to a broke skeg on the original. I only have about 2 hours of welding labor for trade on this motor. It had been sitting a while and the PO didnt need any longer. I bought a new impeller and noticed the drive shaft seal was very hard and dry. Thr drive shaft came out with no resistance even with the LU full of oil. I havnt done a repair like this on an outboard. What are some tips, tricks, or things I need to know and watch out for? It is on a 1989 johnson 25 hp, J25RCEM.