The basic stock style replacement parts all seem to be the same no matter who sells them. www.laurelmountainmustang.com usually has cheaper prices. I think some guys use maier racing for more options on spring rates for more performance applications. The grab a trak kit seems to me to be standard parts with a mustangs plus label. You can get all the parts at laurel mountain (with better shocks) for a lot less
After having owned about 11 Mustangs in my lifetime and having done endless mods to them, I can say this...
Stay away from oem unless you are building a concours or points car. Since you are ready to replace some suspension items, might as well fork over some extra cash and improve the drivability and safety of your car instead of time machining back to 40-60yr old technology.
Maier Racing for good oem type parts but better than oem.
Total Control Products(TCP) and Global West for top end bolt on suspension parts, pricy but well worth it. All tubular, coilovers for front and rear, ect..
Want to go all the way to the top? Custom made parts..
I have Global West on my 65GT, TCP on my 70 302 Boss, and Global West on my 71 Boss 351. Very happy with all of the upgrades.