Not sure what you have, here are some references with descriptions:
low hump. 1978 2wd, 3/4 ton:
1983 K5 4x4
1980 2wd 4-Speed high hump
73 K-20 Auto, 4X4:
1980 c-10 1/2 low hump:
1981 low-hump (2wd, 1/2-ton)
1991 Crew Cab 2WD 1T High Hump
1986 K-30 Automatic Hugh Hump
1984 K5 4x4 Automatic
1986 K30 CUCV M1028
1983 K30 dually 4speed 4x4