How I really learned to shift even though I already knew how to shift. With a farm and two scrap yards plus house with a big yard I think garden tractors were what I first learned. Our Model A Ford meant always knowing a double clutch and matching RPM. As a teen I started driving our old Mack B-61s around to dock trailers or dump trailers. At 18 I got a chauffeurs' license and was shuttling trailers around town and short distances with a 1959 Mack same birth year as me. This is also why I have hearing loss. This seems pretty quiet for an old Mack. My favorites were always Roadranger 13 speeds. That split from the overdrive made a difference if you were underpowered or if it was serious climbing. For twin sticks the 4x5 or 3x5 were actually easier than 3 by x because you don't have as many splits. I'm guessing @Toto'sDad knows that one. I don't know about modern engines but I liked Cummins Formula 400s and Cat 3406. Detroit V8s that sounded good to me got old really fast when they're wrecking your ears and brain.