I going to assume :rolleyes: that the reason they say 75-79 is the vent on the front drivers side that is for a (smog) hose to the air cleaner. They will work, as repros' fit,

,just plug the vent. Perhaps some one has experience with them.
Larry
68 C20 327/465 daily driver
63 C20 292/420 Camper truck
65 C10 ? /powerglide Custom Cab AC,PB,PS,$flashe
70 C10 250/3spd org/Gauge dash,Wood bed, 4Sale$1300