Oh, and in case anybody's wondering, it took a solid three weekends to make this happen.
First w/e: Pull donor motor. Pull it apart, replace gaskets, clutch, etc. Cut off motor mounts (reciprocating saw w/8-12" blade worked well)
Second w/e (snip from an email I sent to a friend):
Last weekend, I cut the motor mounts out of the blue Jeep. While I was doing that, I realized that the fenders were completely in the way, and would be in the way when it came time to weld the motor mounts into the red Jeep. I also finished going through the new motor, installed the flywheel and clutch, and reattached the transmission. I also started tearing down the red Jeep, mostly underneath -- disconnecting driveshafts & wiring, draining fluids, etc. One night last week, I pulled the whole front clip off of the red Jeep. It wasn't terrible... mostly just a bunch of bolts (air ratchet was exceptionally helpful here). As of Friday night, the only thing left on the 4cyl was to drain the power steering fluid and unbolt the motor mounts.
Saturday, it rained all day. I put out the EZ Up and still managed to get some stuff done, but it mostly sucked. I got the 4cyl pulled, cut the 4cyl motor mounts off, and swapped the input shafts on the transfer case.
The plan Sunday morning was to swing the 6cyl in place and weld in the motor mounts. I figured that if I had them bolted to the motor, they'd sort of self-locate on the frame. That didn't exactly work out. I used the transmission mount to hold the trans centered and located fore/aft, but the engine was still swinging in the air, and didn't really want to settle down hard on the frame. So I took careful measurements off the old chassis, unbolted the motor mounts from the motor, and tacked them to the frame where I thought they were supposed to go. I set the motor down on them, everything looked good, so I burned them in. Setting the motor down that last time was pretty awesome.
I spent the rest of the day reinstalling stuff and hooking things up. As it turns out, the chassis side harness is NOT the same from 98 to 99. The plugs where the engine harness attaches are different, and it looks like they have different wire counts/colors. I'm going to have to look into that a bit more. I've got to figure out what to do about the exhaust, fill everything with fluid, reinstall the fenders, driveshafts, and a bunch of other odds and ends.
Third weekend: Build exhaust (helps if you have the downpipe from the 6cyl exhaust manifold to the cat!), install transfer case, driveshafts, install front clip, fill with fluids, modify wiring harness, reinstall transmission shifter & interior trim, adjust transfer case linkage, etc.
I fired it for the first time on Saturday afternoon, but it didn't move for the first time until Monday afternoon. The little stuff sucks up a LOT of time. I spent a LOT of time looking around for miscellaneous fasteners, etc... and I felt like I'd been pretty good about bagging things up in sandwich bags as it came apart.