I am about to find out, sorta .. I bought OEM 6M6-44517-A1-5B. Which I think are the ones being used by a lot of FL riders. They are not a perfect match but you can either mill the bottom 1-2mm or shift the mounts outward, effectively lowering the height.
This chart gives a pretty good idea of what fits what:
http://www.atlanticjetsports.com/motor_mounts_-_yamaha.htm
good price, I wonder if they are WSM ? couch mounts appear to have more surface area for the rubber to be vulcanized on. Berky said he can not break em doing backies...
I ran these same two couch mounts near the bulkhead and two SJ mounts up front with keepers w/o probs...(keepers have to be modded to fit around couch mounts).
But you don't land upside down much, right?
I got a set of brand-new XFT mounts coming.