This must have been drawn back in the mid-eighties. I found a scan of the finished piece online at Comicartfans and I'll include it here for comparison. The sketch has been hidden away for a couple of decades in my files which could really use some sorting out. Eric Delos Santos appears to be the current owner of the finished piece but I don't think he was the original commissioner. Are you out there Eric?
Update: Here's another prelim for the same commission. I don't know why I started over instead of just adding the shadows to this one. Weird.
Durango Kid #10 - Frank Frazetta art
7 hours ago