I got a 64 3/4ton chevy 4spd drive-train 4x4 with a 350. I don't have a tachometer so i was wondering what speeds are usually a good time to shift on flat ground? I understand i can figure it out by using sites to figure it out but i'm unsure of what the gears in the transmission, 1st is something like 7:1. does anyone know what the axle ratio is?