Did it on my 2gm/ 80H-27
It can happen if the nut on the outside of the flange coupler gets loose. You don't have to pull the boat or remove the shaft to get at it. First,measure the hight of the shaft from the hull.Then, remove the 4 nuts and bolts which hold the two flanges of the coupler together. Then push back the shaft through the log. Tie up or block the shaft so it stays at the same height it was at before you started so that it doesn't droop. The nut is on the back side of the trans coupler. If it's lose snug it up. Usually, it will only leak wher running. If you're certain the seal is bad, remove the transmition by removing the bolts around the trans bell which attaches it to the engine.You will have to disconect the shift cable from the shift arm and possibly unplug the wiring harness at the engine to get it out. I followed this process and sent the trans to Mack Boring in Union NJ. (I needed new cones too). It's easy to reinstall the trans and reattach the coupler. WARNING...have the engine and shaft realigned before running. If you take your time you can do it your self. Or... you can have the yard do it. Get a price ..it may be worth it.
