The seal where the shift lever enters the housing is weeping a little and I would like to change this before it gets worse. Can I do this without dropping the motor and dismantling the case or can I access this while the motor is still in the chassis?
Just need to remove the pinch bolt on the shifter and remove the shift lever from the shaft. It's a good idea to make a reference mark to mark the position of the shifter to the shaft before you do. The old seal can be removed easily by driving a small machine screw or self tapping screw into the center of the seal until the thread grabs the seal giving you something to grab a hold of with some pliers then just pull it out.(Just dont go too deep-again use a short screw) Clean the crud off the shaft and put a little clean oil on the new seal then drive it on with a socket.
I did mine as well, 85 LTD. I had read where I would have to drop the manifold off the head but while I was spraying the nuts that held it in place, I was looking at a straight shot in to the shaft. So, as described above, I just removed the shifter (Must remove bolt all the way), took a hook and pried the old one out, cleaned everything in the area up and re-installed the new one...... Minutes.... it's easy.
If it's a GL1500 we're talking about, then the only common problem is that there is often insufficient room to remove the shift lever from the shaft, due to lack of clearance between the end of the shaft and the frame.
The Fix for that is to use a Dremel Tool with small (1/4" dia) grinding wheel, and remove a small amount (~1/64") material from the end of the shaft prior to removing the lever... then the lever will slide right off, this time and forever after, easy.