Need to check the EGR valve.
305 or 350
in a 1992 mc suburban i get about 12-14 mpg
no.
It is on the back left hand side of the intake close to the left valve cover
The 4L80E transmission
1-8-4-3-6-5-7-2
Relay box.
It is inside the distributor under the dist. cap. The wires that you see on the side of the distributor are hooked to the module.
If its a 3 speed auto, I would say its a Turbo 350. If its a overdrive auto (4 speed) I would say its a 700R4.
NO it will not.
Take it to auto zone and have the codes read for free.
if you call checker, schucks, kragen or murrays auto parts they can tell you exactly the factory gap.