While you can remove the lower unit with the outdrive still installed; the issue is ground clearance. To re install you want the drive level in order to get the driveshaft & water tube gaskets lined up properly. I would not try to do this if you have to tilt the drive up for clearance. It depends on how close your skeg is to the ground with the drive level. So given that the drive should come off to check the driveshaft and u joints; Id say an hr to R&R the drive and 2 hrs to split the upper & lower....figure 3-4 hrs plus parts....
https://www.dropbox.com/s/uddmy0ske6lyg ... r.JPG?dl=0Here's what I rigged up to split the upper and lower. A scissor jack goes under the front 2 bolts and one under each side of the all thread sticking through the hole for the trim rams connecting rod. Works like a charm. Just crank each one gradually and it pops off. This is an OMC Cobra but this will work on most any outdrive.
Lower unit with upper removed. The driveshaft goes in the housing with the blue paper towel sticking out of it. If you look closely, there are spaces for 3 orings on that housing, salt deposits around the lowest most one is what makes it get stuck on. The water tube grommets fit into the housing that is removed in this pic.
https://www.dropbox.com/s/hsu59glgt405x ... t.JPG?dl=0