Be careful- the SBC t-stat is smaller (a hair over 2") than the early Mopar size (about 2 1/2"), although sometime in the late '70s Mopar did start using the smaller "Chevy" size on their smallblocks as well as later on the Magnum series engines; so there is some validity to Summit's claim that it will fit both. There is a difference in the bolt spacing as well as the opening for the t-stat. I'm assuming your Indy intake uses the larger Mopar style, since most (but not all) aftermarket intakes do.