SRW K30 and K20 differences

[MJN]

Originally Posted by SunSoaked

K20 generally had SF and the K30 had FF. I have a K30 in my K20. Had to relocate spring perches and shock mounts.

This is somewhat incorrect. K20's had 14 bolt full floater rear axles as standard equipment, the 9.5" semi-float 14 bolt didn't come around until '81. Yes- K20's from 1981 and after had the semi float but they could also have come equipped with the full floater depending on the GVWR.
K30 frames are 8" tall behind the cab vs 6" tall on a K20
K30 rear shocks are located inside the frame vs. outside the frame on a K20
Lots of rear spring info in these info packets outlining the different spring packs between the two;
https://www.gmheritagecenter.com/doc...olet-Truck.pdf