The exact snaps that are pictured in the Big Bass Zone book are a little hard to find. I believe they're called coastlock snaps (that's the style anyway). I've seen them for sale but typically they're attached to a steel leader for saltwater fishing.

I mostly use the stock snaps that you get with a 9" MS Slammer. I've been told they are 65lb rated but I don't know what the mfgr is. There's also some cool little snaps from Japan called Egg Snaps that I got a few packs of but they are probably very hard to find in the US. I've been meaning to get more info on the MS Slammer snaps and update the holistic swimbait article but I haven't gotten around to it.