Pretty sure Vengefuls weren't classic. Not at launch. I can't find the patch notes that added them, but then again they weren't in the habit of spelling out quests and quest mobs in patch notes.
Hard to prove of course, but all the guides from early 1999 for barbs say nothing about watching out for vengefuls. I did find a 2000 post from eqatlas that said something about "now there's vengefuls"... link:
https://msu.edu/~oconne53/eqatlas/everfrost.html