Converting FS to FS2 is only the body, chassis and rear springs. The FS already had the RB5 mid arm conversion and all the other stuff listed in the marketing material. There were no alloy rear uprights. It seems that the marketing material refers to the difference between an SP and an FS2.
InfernosOnly has some good photos of the FS2
http://www.infernosonly.com/PhotoGal...PhotoNumber=11