I have a 88 5.0 and i want to put a bigger throttle body on it but dont know how big i can go or even what size the manifold is. I beleive my options are 60 mm 65 mm 70 mm . but i think it will be useless if my intake opening is as small as my stock throttle body. does anyone know how big the stock throttle body is ?

 

stock throttle body is 60mm, you can go up to a 65mm a 70 will be to
big for stock applications, but you will need a 65mm or 70mm egr spacer

 

Don't bother changing TBs on a stock intake.