Thanks, Still new to these trucks, why do you recommend non-synthetic lube?
The synchros were not designed for slippery synthetic lubes, hence the synchros might not slow the gears quick enough to make a nice quiet shift.
None of the first gears were synchronized so you must be at a complete stop to make it a grind free endeavor. If it is a sm420 4sp with granny low, 2nd gear is synchonized which is the gear you normally start out in if you are not fully laden.