I had a stock 351m 400b in a 77 t-bird it was the most gutless pos ever, I wound up ripping it out and dropping in a mildly built 351c and it was outrunning cars that my friends had that I saw nuthin but tail lights from before. 351m is a over emmisioned power starved low compression nightmare if you want better economy get a m, if you want to have a little pep in your step go for a c or w
