Wanted to introduce myself first properly before start posting here, but this seems important information, so here's my experience with RF speakers:
I put RF T2652-S 6.5" speakers in the front of my 1995 K1500 ext. Cab and they do sound great for my taste. In the back, I planed to put RF T1462 speakers and they did not fit. I would have had to make the cutout bigger so the basket of the speaker would fit. I didn't do it at the end because I don't really care about the rear speakers enough to cut sheet metal. Was a bit annoyed though, since it's a pain in the but to get there.
I'm not sure if the cutouts on the 1997 ext. Cabs are the same but I would assume so? Your truck is two years younger and with a 3rd door and you're planing to go for the P1462 and not the T1462 like I did, so take this information for what it is. Just wanted to give in my two cents.