Mopar ecm issues. Why wont they work?

My 80 slanty Volare leaked it's jelly out in the early 90s, But kept right on running even on the day I sold it last summer. I even borrowed one day when my Orange-box died, and subbed it in for my 367HO, which ran fine on it until I got a new one for the Barracuda. It's probably still running on it. That's about 30 years on no jelly.