Spark Plug Size Question
 

I need to change the spark plugs on my 89 gmc jimmy, 4wd, 4.3L, 2dr. I have browsed the forum and it seems that the ac delco plugs are the winners. However, when searching part stores I keep getting only one available ac delco plug type which is #CR43TS. It seems like a pretty basic plug. I would like to have an overall better plug in the truck, preferably iridium plugs. The specifications for the CR43TS are 5/8 hex, 12.3mm reach, tapered, and 14mm thread size. While sifting through napa online I came across more ac delco plugs: AC 41905 platinum; AC 2 Rapidfire; AC 1 Rapidfire; and AC R42TS; all of which have the same specifications as the CR43TS. Will these alternative plugs work? What am I missing as far as the differnences except for the obvious platinum? Why wouldn't any parts retailers offer these other plugs if they have the same specs? Thanks in advance!!!

You can also use the AC/Delco #41-803 platinum gapped at .045"

ive got a 99 blzr 4.3 and ive changed my spark plugs to bousch platinum iridium 4 pt.a little pricy though but they work out fine go them at advanced autoparts.for the wires got taylor performance wires

You could use an NGK UR6GP or UR5GP in your engine both are platinums. the Higher # is colder plug. I use the UR6GP in my 350 and our 11 second drag car uses an NGK plug.