That price isn't significantly different than most 18" a-arm kits and if anything is on the lower cost end, sooooo the "reason" would be nearly universal for whichever truck he went with (anything truly long travel = not cheap). Thanks for the link to the other thread, but kinda irrelevant to the opening question to this one as it was more about compatibility vs cost, and yes I see where it would go next based off the other thread. At least this guides him what kits he can shop for...
Jakob, what year Silverado SS are you working with?