Small update: a friend of mine sent me this apparently there is a hidden plug underneath the plastic bit seen in the pictures above. I saw it on a couple other GM ecus from around this time period....

Looks like you're definitely right! If anything the outside box and connectors are identical to the 98/99 trooper PCM
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Here is the pinout for the 3 connectors for the PCM
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So you believe the AMD flash chip will contain the EGR map? If so that is what I'll do, I'll find a reader for it so I can hook it up to my computer.
Here is the outside case for the PCM there is...

To start, I'm new to this board so hopefully my project I'm embarking on will be welcome here and there will be folks here both interested in helping as well as knowledgeable enough to help me in the...