I found it WAY easier to do it w/ the bell housing on the bottom and the gear case on top. The ring bearing opens up because the plastic isn’t the tightest. The rollers lean out and make it almost imposable to get the bell housing over the gear case. When you place the roller bearing into the bell housing side it can’t open/expand because it is in the sleeve on the bell housing side. All you have to do is lift the gear case and put it on just like you would do w/ the bell housing side. I spent hours on top of hours trying to get the bell housing to snap down. The shafts are easy once you get the hang of it but even if you get them lined up it wont snap down if the roller bearing is in the way.

Doing it w/ the bell housing down and gear case on top I can get it together in less than a minute.

Oh, you need to let the gear case sit on an angle for a few so all the oil can drain out. If you don’t you get oil dripping out when you turn the gear case upside down.