The oil crisis hit the USA in 1973, and gasoline was nearly impossible to find in places. The price shot up and big engines were doomed at that time. The performance cars sat on used car lots for pennies on the dollar, and new cars were anemic at best. Edelbrock came out with a couple of stopgap intakes, such as the S2P2, and Streetmaster to try to get good mileage and torque. I believe the Streetmaster was introduced around 1974-5 time frame, but can't be sure my memory is correct. About the only performance intake was the Port O Sonic, and F-427 if you didn't have a Sidewinder, or TW. Times were bleak for a few years for the FE. PSE was a stop-gap, but expensive and hard to find. I believe there is a casting date on the early manifolds. Joe-JDC