Those who do not want platinum-tipped plugs in their LT5s and who are confronted with ACD's discon. of the FR2LS, need to look at either NGK or Denso for non-plat plugs.
Keep in mind that the original LT5 plug was the FR1LS not the FR2LS. The engine was designed with that plug in mind and the FR1LS was released back in 1989 for that application. Shortly before the 90s went on sale, GM, nervous about pre-delivery plug fouling problems, changed the LT5 to a plug one range hotter. FR2LSes are too hot if you drive the car the way it was meant to be driven. No one except waxers who trailer their cars--and, thus, see lots of starts w/o warm-ups or people who drive real easy needs a plug as hot as the FR2LS.
The closest thing ACDelco has now to the FR1LS is the Rapid Fire #9. The original RF9 was a non-platinum plug that nearly duplicated the FR1LS but with some revisions for higher-performance. The current RF9 is a single-platinum, like the 41-602, but it has some additional performance features.
With the discon. of the standard type ACs and the conversion of the RapidFire line to a single-platinum tip, there are no non-platinum tipped ACs for LT5s.
For those looking for the durability of platinum plugs, the 41-602, a single-tipped plat., isn't a good value for the LT5, anyway. The LT5 "waste-spark" DIS needs a double-platinum tipped plug, otherwise the durability advantage of a set of plats is negated. Four of the plugs in an LT5 fire with reverse-polarity. Electrode errosion goes the way of current flow. For that reason, to get the durability benefit of plats in an LT5, you need double plats. Use a single tip plat in an LT5 and you need to understand that the durability of the set of plugs will be no better than that of non-plat. plugs like the FR1/2LS
Actually, I have used double platinum plugs in my LT5 but not ACDelcos. I've used the NGK BKR6EP-11. The NGK double-plats are a different design than the ACDs and are less suceptible to the failure of the bonds between the platinum pads and the center electrode. I've run the BKR6EP-11 with good results.
The sraight/crossover, NGK equiv. of the FR1LS is the BKR6E.
As for Denso, its equiv. to the FR1LS is the Q20RP-U11.
Lastly, it was mentioned that the NGK 7 heat range plugs are good for boosted engines. I've run the NGK 7 and, even the NGK 8 heat range, on the street in LT5s with no problems. I'd recommend the 7 heat range plug for street-driven LT5s that are driven aggressively whether they are stock, boosted or otherwise.
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