I think Chrysler called the nylon coating Silent Glide, as it was to make the chain run more quietly. They came in from 1965 on and lasted the life of the engine series. Other manufacturers did similar. It is also quite a saving in rotating mass, being able to use an aluminium gear, although it is half engine speed, and the chain is still heavy. It is good that they didn't bother with a chain tensioner to fall apart!
Any Jensen with the Chrysler V8 and a nylon covered gear, the gear absolutely has to come out, teeth missing or not! Replacements in nylon are not available. It was a hot topic in the 1990s, we assume most were done back then! It is easy to check these days with a phone, pop out the distributor, and stick your phone in and take a photo towards the front of the engine. Here is one I did earlier ! Looks like this one is due!