The 209's are right, I believe. I've seen the other code before and assumed it was a date code. I'm sure a 209 has no variation in function designated by that other stamping.

I don't know of any ground wire between bellhousing and firewall. There's one between block and body as part of the negative battery cable, one between alternator housing and block, and a radio noise suppression ground strap between cam cover and firewall that isn't needed for engine function.

So you can hear injectors clicking on your 83 while cranking? Dang, you're good. Well, I know my ears are bad.

Anyway, the same signal (gray shielded ignition coil #1 wire to ECU pin 1) that keeps your fuel pump relay pulled in provides the timing index for the injector squirts. The injectors are fed in common - all in parallel, one side gets power from the system relay, and the other side the pulsed ground from the ECU at pin 13. A noid light would tell you if the circuit is working. An LED test light at the green/white leads (injector grounds/ECU13) should be winking while cranking.
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Art Benstein near Baltimore

A plateau is a high form of flattery.