Optional rear springs

[sloGMC]

Originally Posted by Dieselwrencher

That may be but I haven't had many Longhorns that didn't have some sort of rear spring option code on the spid

Yup, and it still all makes sense. Those longhorns have optional leaf springs (G60, which includes G50), rather than the base leaf springs (2000# 2-stage leafs-- not G70), which would never be shown on an SPID (again, for Longhorn).

The truth is that between the 3 truck models (15/25/35) and the two sub-models (127"/133"), it is complicated, which is why GMC sent out the Service Letter in April-May, 1971 in post 25 , to "further clarify Data Book specifications concerning the optional rear suspensions available", and help dealers select the appropriate suspension package (post 35)