About 1st gear...that's not good for the tranny but it's normal, you're supposed to wait til the car comes to a complete stop before going to 1st, unless you're downshifting, which doesn't apply to 1st gear. Hope this helps.
+1 If you double-clutch before down shifting, then you are doing the work the synchromesh is meant to do. ie. match the engine speed to the speed of the car for that gear. I assume tractor-trailers have no synchros since there is little difference between engine revs between so many closely spaced gears...and the revs are also so low too.About 1st gear...that's not good for the tranny but it's normal, you're supposed to wait til the car comes to a complete stop before going to 1st, unless you're downshifting, which doesn't apply to 1st gear. Hope this helps.