Ok, get ready as this can get confusing.

#1. There is no PROVEN difference between a 1970 340 T/A - AAR 340 Six Pack engines valve covers and any other 1970 (or early 1971) 340 4 barrel valve cover. However, there were some possible variables, any of which COULD be found on a 1970 340 T/A-AAR 340 Six Pack engine.

This pic shows the most commonly argued variable, some will swear that only the style noted was found ONLY on 1970 Six Pack engines, when in fact, BOTH styles have been found on original examples of EITHER Six Barrel or 4 Barrel engines.