The Porsche 911 changed from the non-computerized L-Jetronic fuel injection system to the Motronic ML3.1 in 1984. The 911 never ran the model ML1.2 Motronic. The 2716 EPROM was smaller than that used in the 2732 used in the Porsche 944.  Read Memory Issues ML3.1 944 for in-depth explanation of the ML3.1 memory structure.

Porsche 911
1984 to mid 1987	mid 1987 to late 1987	late 1987 to 1989
This is a good estimation of the US version 911 ECU.  In Euro/ROW 911 versions and the 930, the EPROM size can vary from this in the