If the dealer for some reason installed the GM 10-leaf spring pack normally bought as an RPO on the original truck, you might assume the dealer installed GM springs were the same as the factory installed RPO.
I do no know how to determine in your 10-leaf 3100 spring pack is an RPO 10-leaf rear spring pack. The 10-leaf option provided 350 lbs of extra load per spring pack.
I do not see GM using the term "over load".
The RPO springs were ordered by the dealer and installed at the factory.
Replacement spring packs could be ordered from GM by anyone - as a part - and installed by anyone.
NOTE: the GM RPO higher weight capacity springs were 9 leaves (standard springs had 8 leaves)
Last edited by tclederman; 04/09/2015 3:36 AM. Reason: documentation shows 8 leaves standard and 9 leaves optional
