I remember several threads about making sure to get the right plugs for Vortec heads, because the old style plugs aren't long enough to make it into the combustion chamber properly. I saw AC Delco "r42lts" and its variants were good, but for some reason, I can't find anyone that stocks them. The only thing I can find is a few of them scattered around on amazon.com of all places... and I was hoping to get 45's, and those arent on Amazon... So what's the deal? Have they changed the part numbers in the past several years to something else?

Why not just ask the parts store for spark plugs for a 1997 Chevy truck with the 5.7l? Those have GOT to be in stock, and are most likely the heat range comparable to delco R45's. Probably a champion cross reference.

Delcos are usually black oxide coated (black plug threads and ground strap), compared to champion/etc which are silverish. Easier to read a plug that's silver IMHO.

I had the same problem. I personally prefer AC Delco's, but I have bought Autolites which are more easily attainable. The Delco's are either R44LTS or the R44LT, and the Autolites are the 604's.

The plugs that come with the Vortec trucks are platinum and the ones listed here are not. My '99 is supercharged, so I can't run platinum, and my '91 with a Vortec isn't driven enough for platinum.

Use Champion RS12YC in your vortec heads.
Champion has a range of different heat ranges for the vortec heads.
RS7YC to RS14YC
RS12YC and RS10YC work fine for typical street strip use.

Those are $6 a piece.

The r45lts is $2 a piece.

I find the platinum/iridium plugs are a bit unnecessary for my app.

listen to f bird 88 on this one bro...i totally forgot about the vortec heads being different when you asked me the other day

Yea, I just figured the parts store could look up the right plug, then you could say "mmkay, gimme that in copper instead" type of thing.

But when F-bird has the p/n's off the top of his head, then damn...