I did my drive service today and my Alpha 1 Gen 2 is not going back on easily. I remember having a beotch of a time getting it aligned last time I had the engine out. Small block chevy, same mounts as the previous sbc, same coupler and same flywheel too. Is it possible to mess up the mounts? Are they side specific or anything? It's tough to lift my engine but I could if I had to.
I plan to start with rechecking the alignment.
Any body have a one man method that works best?

Insert alignment bar and use your hand to smack it a bit up/down/left/right/ diagonal a few times. Pull bar out and reinsert and remove using 2 fingers each way. If your unable to do this, it needs adjusting further. Look at the grease marks on the alignment bar to determine which way to go.

I use the Merc cheater tool which tells me exactly which way to go
P/N 91-863372

AD what is this “merc cheater tool” you speak of? I struggle sometimes with alignment.

If it went on easy last time, maybe the splines aren’t perfectly matched going back on his time. I have a few real dull aluminum props i put (just one)!on prop shaft so i can turn driveshaft easy if i need to. With alpha make sure you turn prop counter clockwise to keep shift mechanism engaged.

Its the one in the pic 91-863372 and I just call it that. It goes on the alignment bar and goes against the bell housing. It shows how the front mounts need to move even if its at a angle.

Back to the OP, if the rear mounts are starting to collapse then they may need replaced. If they are, then no matter what is done the bar will have a hard time going in

I have the one that looks like a long shaft that slips all the way through the coupler. Think I got it on Ebay. You put a coat of grease on the end of the tool that goes in the coupler, then pull it straight out and "read it" with the grease. The grease "splines" need to be even all the way around. If they are not, make note of where they have been wiped off or conversely, untouched, and move the engine around accordingly. Hope that helps.

So, as per usual. the "damage" was self inflicted. I had taken some wise sage's advice last time the engine was out by loosening the mounts and bringing them out with the engine. Installing the engine without hanging off the front eye was my mistake. I ended up with the front mounts so far to starboard that installing the drive was a nearly impossible task.

I didn't work this out til I had spent a few hours running the front mounts up and down repeatedly today.

The only way I could move the engine was to back the boat into my garage where I have a chainfall. I had to lower my trailer and truck tires to get the boat in there. I was using a pipe in the coupler to get a general idea of where the engine was pointed when my brother stopped by to return a tool. He had the idea to measure center off the boat's towing eyes. Once that was done I centered the engine and did a normal engine height alignment. That went fine.

It still took some time to put my drive on. Partly because I am recovering from shoulder surgery, and partly because it's hella hard to pick up a drive under a swim platform.

Little off topic here but if you search through forums you can find example/ drawings of how to build a stand to pull drives. Some cutting and welding nothing difficult. Saves the back and very handy to store drive, work on, paint, whatever.

True, I have a rudimentary stand. I think I will have to improve it to allow better access. I built it when I had a previous boat without a platform blocking the area just over the drive.