I have a big block olds in my 62 c10 shortbox. It fits really nice. cutlass headers work with out cutting and it will really haul the mail. 13.00 without tuning. It is a 425 olds from 1966. 365hp out of the factory. Olds motors make a TON of torque down low. My engine pulls extremely hard up to 5500. but thats all you need on the street. Just my two cents.