According to a book that I have called Mighty Mopars 1960 - 1974 (before anyone asks its out of publication).
The Scat Pack seems to have been a Dodge advertising campaign starting around 69. Can't find a difinitive date. It included all the Dodge high performance V8's in all of Dodges Models.
The Scat pack dress up package was also offered for sale on older Mopars. It included chromed valve covers, oil filler cap, air cleaner, hood pins and locks, and chromed road wheels.
They state that in the 1971 Scat Pack brochure the Mopar enthusiast was urged to join the Dodge Scat Pack Club. For the princley sum of $5.95 you received:
-an illustrated tune up tips folder
-a hustle stuff parts catalogue
-a pocket pack all weather racing jacket
-an offical club blazer patch
-a "Scat Packers unite" bumper sticker
-an official club identifier folder with four pages of Dodge Scat Pack club accessories
-a dodge Scat Pack Inside Outside decal
-a wallet sized membership card
-Scat Speaks, was a quarterly featuring club news, service and tune up tips and other articles
-a 1971 racing guide
-Dodge performance news - a monthly four page flier about dodge racing activities across the country
If I find anything else in my library I will post it.