Check 4btswaps. They usually have "reasonable" prices. That's one of the major downsides. I'm not planning on paying more than $2000-$2500 for mine. Those places on line are usually way above market. I played with fitting a 5.3 in my 6400, but it was a horrible fit. It could have worked. Anything can. But I was going to have to move the steering box (not just a little like with sbc conversions), and the stock exhaust was no where near fitting. I like factory frame suspension and steering, so I sold that ls motor and started looking into inline engines again.