Thanks Carl, good to know what I'll see when I get there! I didn't realize I had to drive the pin to get the hydro end of the coupling off, will get that sprayed up first so it won't be too hard to push out. I've got a screw in seal puller that hopefully will make quick work of removing the old seal.
I just picked up the seal yesterday. I noticed that once the tractor sat for a day there was no oil dripping so I figured it might be above the level, and you confirmed it. But, my oil level is already low from the leak, and I don't know for sure that the prior owner changed the oil and filter though they both look fairly clean, or what oil he put in. Anyway, I decided to change the oil and filter while I'm at it, so everything will be clean, full, and ready to go.
Glad to hear the 1811 is fixed. That's a great tractor, we had a 1211 that did a lot of work for us, in the end I would have kept it if it was the 18 HP like yours but it had the 50" deck and struggled to cut if the grass was high. As much as I like my 1864 and 2084 I still think the 1211/1811 design had some real advantages, the top mounted fuel tank with gauge and steel hood to name a few.