A little searching through GMPartswiki came up with the result in the 1st pic below for your '79 C10. The Lock, Ign (Coded w/key), GM# 7833759 is the correct original lock cylinder for your application.

Here's an NOS original Ignition lock cylinder with keys (2nd picture below from the ad) for a fairly decent price. Hope this sets you on the right path. wink
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Last edited by Gdads51; 04/07/2025 3:02 AM. Reason: edit double words
~ Dan
1951 Chevy 3 window 3100
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"My Grandpa Carl's Truck and How it Became Mine"
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US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)