i know marlin is probably the best but there out of them right now
they are all the same just tiny little difference to keep them away from each others patent. 421 has two of them for his triple case they went together nicely and looked just as beefy as the marlins All it is, is an aluminum plate with two bearing and a coupling not much can go wrong there they also have the 23 spline for the same price 299 is a pretty good price.plus a lifetime warranty is pretty nice to have
I'd just wait for Marlin to get in the one you want! The one thing about MarlinCrawler is you got to be patient!