I'm old enough to know more, but I have forgetful mind in my old age. I bought a real clean 80 r-model dump truck couple years ago, 2 stick 6 speed. A Mack mechanic at dealership told me to never ever do any thing other than when leaving pit, use first gear, low range, shift to high range on highway and just drive it like 5 speed. Well, bout the last month I been shifting 1,2,3 low, then go to high side after winding 3 low out, gear ratios are spaced closer like that, faster recovery time, less jet black smoke, and nary a scratch of any kind at all. I even downshift high to low sometimes on ce