Brent, I recently did a short for long cage swap. I don't remember precisely what the hurdle was, but it wasn't quite as easy as changing the short cage for the long cage. Give me until tomorrow afternoon and I'll try to give you some more details. If I recall correctly, the mounting bolt that goes through the RD body and threads into the cage was slightly different (not the mounting bolt that goes into the hanger, but the other pivot bolt). That bolt threads into another section, which then threads into the cage. I believe I had to swap both the cage and the other pivot mounting bolt.

I went from this:


To this:


Btw, recognize that FW?

P.s. Sidenote: Another difference I noticed is that the b-adjustment screw also went through some subtle changes as this derailleur evolved. The b-adjustment screw on the GT version (from which I grafted the long cage) is slightly wider at the head and does not clear the RD body of the short-cage body enough to provide the same range of adjustment.