The LS3 engine was offered to three different types of vehicles, the Pontiac GTO, Chevrolet Corvette and the Chevrolet SSR. About 1998 is when they started installing these motors.
The GMPP Catalog lists the weight of the LS3 crate engine at 415 pounds
In GM trucks or new GM cars, the 8th digit of the VIN # is the Engine.
Ls3 v -8
430 in a stand-alone crate application.
7.6 litres
No
GM Cars + Trucks (80-05)
Your going to need the proper wiring harness to make this work. Aftermarket harnesses are available and would spend the money for it as this is a great swap using the LS3
You can find GM cars for sale at a dealership that sells GM cars. Also, the local newspaper is a great place to seek out classified ads for GM cars that owners are selling for fair prices.
This motor is not compatible with diesel engine parts. As this motor is generally used in smaller GM cars that are a little more than lightweight. You would need a motor for a GM truck to match with diesel parts.
If you expect an answer then you need to list exactly what make, model, year, and engine size you are talking about. GM makes many different cars with many different engines.