Hello,
I am a GM retiree. I have some knowledge of GM powertrains.
I have a 1977 Black Crew Cab Dually. It had originally a 7.4L THM 400 and 4.10 axle.
Now the truck has a 468 cu in oval ported head, flat top pistons, reman engine with a cam of higher lift/dur.
I have the first released...