what kind of carb do i have

[ottaway]

i just started working on a 77 GMC 1/2 ton with a 454 and i beleive im gonna need to work on the carb.
does anybody know what kind i have?
its the original carb it came with and it is a 4-barrel
it is not electric choke, but it isnt a manual choke, looks vacuum operated and most of the choke linkage is inside the carb, not outside like the m4me in my 83 4x4
it is a rochestor

[Pontiac1976]

Most likely a Rochester with a intake manifold heat operated linkage.
use some carb clean on the carb front right and the back mostly to clean it so you can get some #'s. Does the inlet for the carb point straight out the front, or does it point out to the right side of the truck.

if Rochester
if Pontiac carb fuel inlet points straight out.
if Chev carb fuel inlet points point out to the right side of the truck out.

Find the # carb you should see the name, on driver side near the back center once you clean it off a bit.

could be a Holley but most likely Rochester
or few pic's.