is there some relatively clear instructions on how to put an R6 rear end in the GS?

Yup.

http://www.customfighters.com/forums/showthread.php?t=37843

Quote from: fraze11 on June 13, 2012, 04:30:33 PM
Yup.

http://www.customfighters.com/forums/showthread.php?t=37843

ok thats a whole lot of pictures but nothing in writing as to what is going on

You could always join that forum and message the guy.  He'd probably be happy to share how he did it.

cf rocks but gstwins still better,....my .02