Starring: Richard Locke, Jack Wrangler, Steve Boyd, Duff Paxton, Kurt Williams ("Desert Rat"), Dane Tremmell, Skip Shepherd, Bud Jaspar, and Maria Reina (Boyd's girl - non-sexual role).
So, the previous scene shows Jack whacking it in Steve's imagination/dream. Just after that Steve wakes up, and whacks off while Richard Locke continues to drive the truck, and whacks off as well. Falling back asleep, Steve imagines his first gay sexual experience, with Jack giving him a blowjob (and some Dos Equus for lubrication!)
update - OOPS! I forgot the link for folks who want to download ------ Click one of the pics to view the movie trailer (you know that if you view the clip in the browser, you can "right click" and view it FULL SCREEN, right?), or here if you want to download and save for later.