Looks like I got to much carried away with idea and made a mistake with my numbers. I also neglected to double check my calculations before posting original message.
Now that I have redone my calculations I get the right numbers ((first gear)27.22:1; (second gear)18.88:1). I am totally puzzled as to how I managed to come up with the wrong numbers.
My apologies for posting wrong info and big thanks to joules for providing correct info.
Mathematically calculation of final gear ratio is simple ( [
] ), once you figure it out of course:
Divide teeth numbers of gears the mesh with each other and multiply for gears that sit on the same shaft to get:
43 / 13 * 29 / 32 * 44 / 18 * 52 / 14 = 27.22 -- 1st gear
43 / 13 * 29 / 32 * 39 / 23 * 52 / 14 = 18.88 -- 2nd gear
Seems like I was wrong in my original assumption that truck engines never reach top RPM.