*WIP*
Generally, this is an 87 only mask, but also appears to have been used on 2.5 A-bodies up to 89. kind of an oddball ECM, it looks like GM was making a reduced-cost 1227165 derivative. anyways, it appears to need a 10K resistor active for its datastream, with no commands sent to the ECM(so, uni-directional 8192), the ADX is setup to reflect this(and was tested on a 89 celebrity).
XDF attached.