Many people buy 2 rear mains because you're almost certain to mess the first one up when trying to install the upper portion, but I learned a fantastic trick on my last one. Find some very thin plastic and cut a strip that can be folded over and inserted into the channel to serve as a "shoe horn" for the outer edge with that fragile lip. You can't use anything as thick as most soda bottles, nor would I use something like a plastic bag. Look for something extremely thin yet with some rigidity. I did my last one after Christmas and my son got a set of toy tractors and the front of the box that they came in was a plastic display window and that is what I used. I cut a little strip out of the window, made it pointed at one end and stuck it into the channel where the seal goes, and used it to guide the seal in. Make sense? Leave enough hanging out so that you can pull the plastic back out once the seal is in. I also used a medicine dropper to shoot oil in the passage around the crank and between those 2 things it could not have gone in any easier.

 

It really shouldnt be that hard, just cover it in soap to lube it up and I drive them in by hand then the rest of the way with a brass punch. You can figure something out, I guess if you do decide to buy two you might be able to return the other one if you dont use it.

 

My first one was fairly trouble free, but my second one gave me trouble and I nicked the lip. That's why I pass along this info.

 

Turning the crankshaft with a breaker bar helps too when inserting the upper half.

 

Thanks guys for all your input. I will let you know how it goes.