Having a difficult time getting a solution for spark plug replacements for 69 Camaro RS/SS 396 / 325 hp M20 trans. Using (according to specs) R-44N with an option for R-43N if it needs a colder plug. However there getting tough to find. I can get them on e-bay but would prefer to find a more modern plug that's more readily available. Researched 2 x cross reference charts to find a Champion 404 / 415 and AC Delco R-44XL that spec out with 13/16 head, 3/4" reach but these plugs are completely threaded unlike the original R-44 series that are half threaded with the other half plain tapered. I guess what I'm asking help for is what are others using? I believe that the totally threaded plugs were used later that 1969 and most likely used for the aluminum heads for strength, but not completely sure. Would appreciate any and all comments before I burn the new engine in.