[ctandc]

This is just my opinion, after helping with several LS1 swaps over the years (those tend to cost a bit more than the 4.8/5.3 engines). It all depends on what you have, and what kind of deal you can find.

If you can score a decent 5.3 w/ tranny, wiring harness, PCM etc for less than $3K then I personally think the swap is worth it.

If your are doing this to replace a good running engine, then it's not really cost effective.

You also have to price in whether or not your doing the wire harness yourself or buying a ready made harness. Then programming for your PCM.

If you plan on headers, they seem to get a bit pricey.

My son's truck is low buck for sure. And it will keep the 6 cylinder for now, but I'm keeping my eye open for a deal on a 305/350 TPI setup. I'm rather familiar with them, complete systems can be had for cheap, you can adapt a TBI truck / car wiring harness.