When I was on the phone with marlin's the tech told me the R150 fork is different than the R151 1-2 fork.  You might just want to check into it...They also said that the forks are the common breaking point because of the retainer letting the main shaft walk just enough for it to snap a fork.  Upgrade the retainer with the aftermarket one they make, and do the thrust bearing and it shouldn't happen again was what I was told.

I will check out your thread, gonna be a while for me as well...Gotta swap motors in the car before i can park and work on the truck all the time.