QUOTE(Root_Werks @ Mar 18 2010, 07:57 AM)
Green is CIS engines like 2.7's.
Black is what I think you want to look for?
Green shrouds were introduced with the 1969 911E (2.0) and red shrouds of the era designated the 911S. 911T shrouds were black until the 1972 911T (2.4), when the yellow shroud was introduced. The 1973 2.4T CIS engines had black shrouds. With the introduction of the 2.7, the plain 2.7 had a black shroud, IIRC, and the S had a red shroud. Seems to me the "Carrera" version had a red shroud as well, but that makes sense as the 1974 Carrera was a tarted up 911S. Same car with modest rear flares and trim options.
Later shrouds (post 1971, I think) offered improved cooling, and can be identified by the removable oil cooler "bump", as opposed to the fixed style.
The Cap'n