For 73-87/91 trucks...
Blazer 106.5"
PU 6.5' bed (short) 117.5"
Suburban 129.5"
PU 8' bed (long) 131.5"
Crewcab 8' bed 164.5"
So, yes, 117.5" is right, center of front axle/wheel to center of rear.
There are some other flavours for cab & chassis, but they're pretty rare.
-- A