you drill out the rivets holding in the crossmember mounts with a 1/4 drill bit, whack the heads off with a sharp new chisel, and reassemble in the other three holes that are 2" forward of where it used to be using appropriate grade 9 bolts and nuts with a bit of locktite. the front top hole becomes the new rear hole.
annoy the neighbors with the banging and swearing, bash your knuckles a bit, have a beer, you're done.
BTW do the above with either the tanny/crossmember out, or supported on a stand.
OH yeah: go to the tech forum, read the swap instructions.