I am doing a little research on 3/4 ton Chevy and GMC 4x4s. I understand that 4:10 gears are std now along with 6 speed automatics. But, what year did this standardization take place?

My wife just purchaced a 2011 duramax with 6 speed Allison tranie and I don't think that Chevy or GMC puts Allison tranies into gas trucks, but another type 6 speed automatic.

I am probably going to buy a used 3/4 ton within a year and I am doing research now.

I also understand that 6.0 gas engines are now standard but do they burn low-unleaded and ethonol crap?

THX