Might want to figure out what 1979 D-10's are selling for first.
The Big money trucks from 79 have to be the Warlocks, Little Red Expresses , and short bed 4x4's, and Ramcharger in good condition.
May take quite a while to sell a 79 truck if their is nothing special about it, or even if there is something special about it.
Easy to put more into an older car in repairs and cosmetics than you can get out of it at selling time.
But if you love the truck that shouldn't matter if you're keeping it....