Got a truck! '76 D100 400/4 spd. shorty

Factory 400 4 speed?

Cool.

My 1980 has a factory 833 O/D behind a transplanted 1969 440.

I do use first but I ain't in it long.

You can start in second if you want, but you spend a LOT of time in second.

It's basically idling in 4th (O/D) at 45 MPH.