Never said that LRE's were not converted. Just not all ME's are former LRE's.
Every truck from 77-80 has a silver bezel when optioned strictly as a Custom or Adv.
an Adv SE will have woodgrain bezel and SE door panels.
an ME is hard to document as it was not a Dodge production vehicle, so it would not have an option code. So yes, you're correct that any stepside truck could be made into one. Just like any 76-77 can be made into a Warlock and we all know any stepside is a Warlock