ECM on an '86 K5?

I was browsing some archived info here and saw mention of a very low-tech ECM module that would have come on my truck. Again, it's an
'86 K5 Blazer.
According to what little info I was able to gather, the ECM was connected to a knock sensor and could monitor ignition timing. The latter part got my attention.
Is this true regarding its ability to monitor timing (advance)? If so, is there a way to tap into it or read it somehow to output it to a gauge to monitor the timing real-time from in the cab?
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