ECM ID

[bruce plecan]

Orin
There "should" be a paper label on the ECM itself.
It will Either start with a 1227, followed by 3 digits,
or 1615, followed by 4 digits.  If not a parts house might
help, but I'd be more tempted to seek a dealership for
id. help.
The 1615 is the newer series of numbers for the ECM,
may be for PCMs, only, anyone?.
The 165 refers to a 1227165, 747 refers to 1227747,
748, 1227748, and 749, 1227749.  BTW there seems
to me more mention of the 148 rather than 748.
The 165,+730 used in some GM Cars 86-89
The 747 used in some GM trucks 87-93
749 Syclone/Ty various other turbo applic, and others
148 GN (86-87) TTA, and various other FWD
HTH  Bruce