I think a lot of that had to do with the fact that some states restricted the sale of the L-82. In 1978, The state of California mandated the installation of RPO YF5
(California Emission Certification) which dropped the output of the L-48 from 185 horsepower to 175 horsepower
and 270-pound feet of torque, in part through the use of an altered carburetor
and distributor combination. This same limitation found its way onto Replicas
sold in the states of Maryland, Florida, Oregon and Washington, as well as cars
sold in the cities of Boston; Chicago, Des Plaines and Barrington (Illinois);
Grand Rapids (Michigan); and throughout Cook County (Illinois). Cars being delivered to higher elevations
(above 4,000 feet) required High Altitude Emission Equipment (RPO NA6). They also received this detuned, 175 horsepower, L-48 engine.
Also it is my understanding that all cars with RPO YF5 could only be ordered with an automatic transmission, no 4-speed manual transmissions, just automatics only.