which AC Delco spark plugs?
 

What is the correct Delco spark plug number for a '99 Bonneville SE?

Reg plats are #41-921, for the Rapidfire it's #14

I had a dealer send me spark plugs (#41-921) and wire set (#746DD) for the '99 SE.
Unfortunately I now find out those part numbers he sent me are for 2002 SE.
Is this a problem?
Part numbers for 99 SE model year are #41-101 (plugs) and #766E (wire set).

The spark plugs are right on the money that the dealer gave you. The wire set should work to as the only difference is slight variance. :wink:

Rat,
If the spark plugs are right on the money then why does Delco's website list part #41-921 as correct application for the '99 SE?
He sent me #41-101 which according to the website is for 2002 model year.
Also, Delco's spark plug product description (website) says :
"The prefix #41 stands for spark plug, numbers after the prefix indicate the type of plug and also the specific application 100-199=Iridium, 600-699=Resistor, 800-999=Double Platinum"........."Numbering: 1st number denotes thread size"........"Second number denotes heat range....the numeric code does not in any way correspond to the heat range of the spark plug....Therefore, selection of a spark plug with a different code number is not recommended....The heat range may be drastically different between two different plugs and engine damage or poor performance may result".

Rat, what is your opinion of this info from Delco's website?

Don't worry about it. They will work. You have the exact same engine (L36) anyway.

The reason that your PN is different than a '02 SE's is because (I am assuming) GM stopped using platinum plugs as OE and started using iridium plugs instead.

Iridium plugs are fairly new and are supposed to bit a little better than plats, however in real life I doubt there is that much difference between the two and they should work equally well with your car.

Same with the wire set, you have the same engine and I doubt they will be a problem.

I just did my plugs and wires on my '95 and I used the NGK iridium plugs and aftermarket wire set. Both items were for a '97+ gp and it all works great.

That's exactly what GM did! The 921's are the old GM number, while the 101's are the new NGK Iridium number. You see GM started using NGK Iridium plugs in 97 in the new 5.3 Vortec engine. Since then GM has now decided to use the NGK Iridium plugs in all their cars/trucks. The phase out started this year. Our shelves at work still have some old GM plugs, but that changes as soon as we get in newer stock as GM now sends only the newer style NGK built plugs as substitutes. :wink:

Rat and others here, thanks for the good information.
I did call AC Delco customer service today.
Sales rep said plug #41-101 is replacement number for #41-921.
Rep also said wire kit #746DD is replacement number for original # 766E.