date coded mufflers for 68 charger rt

[RT440A833]

I have a no.s matching 68 charger rt 440 and want to order date coded hemi mufflers but im just a bit unsure on which date code to go with. The car was built on Feb 2nd and i want to know if the date code would be 967 or 968?

[hemigeno]

If those are your choices, September of '67 (967) is absolutely what you want.  The other would work for a '69 model.