Need to replace the rear end in my F150. I nned to know info on matching up the gear ratio with the front transfer case so all wheels will turn equally in 4WD. Info I have - Axle ratio, 3.55. Axle code, 19. Does this mean that I have to find a rear end with 3.55 gear ratio? I am not a mechanic, but would like to find a used rear end to go in.