Thinking of changing gears in my 93 f-150 4x4 rc stepside 302 e4od for pulling my holiday trailer easier(its a big girl 32 ft long and 12000 lbs). I did a maiden voyage the other day and wow it did not too bad at lowwer speeds, up to 80km but over that it was not pretty, I need either another 100hp or lower gears. my question is if i drop down from my current 3:55 gears to a 3:73 set, how much would my rpm change. currently i travel at 100km at 1800 rpm. Thanks