I already posted on the first page! But yeah, I actually really do like the 4.3L V6. It's not quite enough for me any more, but prior to the 4L80E swap it had plenty of power. The extra rotating mass of the 4L80E took some pep out of it's step. It's still fine for a daily, but I can't get it to break the tires loose on dry pavement any more. The factory 3.42 gears aren't helping that I'm sure.
Back when it still had a 4L60E it was surprisingly powerful for what it was, though. I could do donuts on dry pavement at will and it ran a mid-17 second quarter mile, which I thought was pretty damn decent for a mostly stock V6 in a full size truck. Also worth mentioning that it's been just about the most reliable engine I've ever dealt with. I do beat on it very regularly, it sees WOT at least once every time I drive it. Roughly 150K miles and still running factory gaskets, injector spider, etc. Doesn't leak or burn a drop of anything. Runs 50 PSI of oil pressure at hot idle, in gear. I just change the fluids and it keeps on taking all the abuse I can throw at it.
I've been half-ass looking for an LQ4 to swap in but I really don't want to until the V6 has an issue of some sort, which at this rate may be never. They're great little engines.