I have a ZZ4 350 and have been having problems with the plugs loading up and fouling out when i move the car around the drive. So i called local parts store to ask about a hotter plug. The Engine came with MR43LTS Spark plugs, the part store sold me R44TS. Both those part numbers are AC Delcos by the way, But my concern is that the new plugs ( R44TS) are slightly longer than the older ones. Am i ok to run these plugs?

 

Those R44TS are actually too short. Thats for the normal SBC iron heads. The 'L' in the other plug is long reach, something missing from the ones you just got. The distance from the tapered seat to the base of the plug (not the electrode itself) should be longer on the 'L' plugs.