Of the ~200 conversions I've done to date I would estimate that I've used 50% short shank, 30% medium shank, and 20% long shank (in very round numbers). About 50-60% have used the scale box while the rest have used the retro-fit shim. I used short shanks in the truck-mount conversions I have done so far. I printed my own box lid for those (with an integrated spring splitter) but Andrew has his own design that he is shipping (or soon will ship?). But honestly, truck mounted gear does not do very well in downgrade situations on my layout, so they will be converted to body mounts as time permits. (Nonetheless, truck-mount N-Ps perform better than truck-mount MTLs.)
I have not actually converted any locos yet, but I have seen Andrew's design for a Kato retro-fit that looks dead simple, so I'll likely hold out for that. (I have a design I could print myself, but it needs tweaking and I have a ton of other conversions to do still.)
I am hoping to spend some of the upcoming long weekend here in BC to write up and post some of the details of my conversions in case others (or my future self) find them useful.
-gfh
