[Shotimes] (OT) Rear suspension question

[Rich Bruso]

   So, I've been considering switching to GM rear arms for a while.  I know I'll need the reducer sleeve and washer kit, and I've seen the disucssion on washer placement.  My only question at this time comes from MidwestSHO's website.  They have arms that are "already trimmed."
   I guess I missed it somewhere, but what, exactly, needs to be trimmed on the GTP arms?
   Also, has anyone adapted the brake bias valve to work with these arms?


-Rich Bruso
89 Black (Lola)
89 Silver (parts)
Sierra Vista, AZ