i took out my old vacuum modulator and there was no color stripe around it...the new one i ordered from NAPA has a blue stripe and came with a gasket...i have a 67 289 2bbl with an auto transmission which is a c4...the guy told me the blue stripe indicates its for a c4, is this correct....and it came with a small circle gasket, does that just go between the modulator and where i screw it into?