Im a couple of months away from a engine swap on my 94 Caprice, and I wanted to know the difference between the fuel pump in the 4.3 and the one in the 5.7. I have a 4.3 now, and Im assuming a fuel pump for a 5.7 will fit right in with no mods.

Also, for those with a 5.7L, what type of gas do you use? I know in the owners manual it says 87, but I know alot of people that put 93 octane in their 5.7. I actually put 93 octane in my 4.3 for the most part because the car runs so much better off the 93.

Finally, does anyone know of a good place to get a good set of gears. Im also trying to put posi in the car, so where could I look into that?

If an engine is designed to run on 87, you will not get better economy or performance by running higher octane. You will simply get a lighter wallet.

Unless you are you and you did your LT4 knock sensor, which allows you to run more advance (requiring higher octane fuel to keep the engine from grenading).

What is your axle, 7.5 or 8.5? I have a set of 3.42 8.5 gears on the back porch. I don't have a posi carrier though but you can probably get one from a junkyard and rebuild it on the cheap.

I believe the fuel pump is the same for either the 4.3 or 5.7 engines - the difference is in the injectors themselves. The 5.7 _might_ have a higher flow pump on it, but it may not. The pumps are interchangeable.

I have the 8.5 in the rear.

Also, the fuel pumps are different because I work at a parts store, and the fuel pump for a 4.3 part number is different from the one in the 5.7. But i figured they would be interchangeable.

How much you sellin the gears for?