I hate to sound dumb but cant help it. Looking at Eaton rears, now is it right that a 3 series only goes to 3.73, and a 4 series from there up? Wanting to run 4.56. Was told I can run higher gears on 3 series with spacer? And whats the difference between truck and car. My housing is off a 78 Blazer. Hate to buy something and find I cant use it.