Any quality rear main seal from a major manufacturer (Fel-pro, Timken, Victor Reinz, SKF...) should be fine. However I noticed a lot of them supply a fiber/paper gasket. I would throw that away and just use RTV, which will be more reliable and durable long term.
Once again, I second this. The first time I did my clutch I did not have a transmission jack, and I spent a significant amount of time trying to get the tranny lined up and cursing it. Last two times I had the tranny down I had a transmission jack and it took me less than 15 minutes to jack it back up, align it, and push it together (bolt installation took a little longer).
Having the right tools takes this from being a real PITA to just a time consuming job.
I could not find or rent a transmission jack when I did my 5speed swap (not quite 3rd world here but close) so I braced the transmission,took off the crossmember and took off the trans mount and bolted it to the jack. When you bolt the mount back to the transmission you have a very secure mount . The R150 is not balanced front to back like this so you need another jack for the front but it will not tip at all side to side. The W59 is lighter and more balanced so you can just counter balance with your hand to pull on and off. Not recommending to do it this way, but some of us dont always have access to proper equipment and am just pointing out another way to do it