YES, It will bolt right up with NO modifying.
It is bolted to the frame and the back of the head. You can put it anywhere as long as it is bolted to the frame and the engine.
In the throttle body.
All the speakers in a 1991 Chevy Silverado should be 4x6 if they are stock.
In the fuel tank
Yes, yes it is! I know i have a 1991 Chevy K1500 with one of them in it.
it's located in the rear of the transfer case
3200
85 mph.
I have 91 chevy k1500, It does this, Sometimes it will idle a few minutes, then jump to high idle and check engine light comes on, And sometimes its as soon as i start the engine... I was told it was a vacum leak, But im no mechanic
R-12 from factory Should be converted to R134
set timing on 1991 c2500 5.7 liter
YES it is.