I just bought a 94 5 spd powerstroke with 4.10 gears and 235 size tires. It is low geared as can be i think the rpms were around 2500 at 70 mph and 2800 at 80. Is 2800 rpms safe rpm to hold steady on a diesel like this if not what is. Sorry for the dumb questions but ive mostly owned gas trucks(1 6.9L diesel 4-5 yrs ago with no tach). and im not real familiar with the newer diesels.