The tang went away in the early 80's. My '84 had a recessed fitting. My '89 and every one since has not had a vang attachment.

Here's the rule on the vang (this applies to all Hobies):
Quote
16.1 A single boom vang may be added. It may be
attached to the base of the mast and/or be
movable from side to side on the front crossbar
for use as a preventer. Vangs shall not travel on
tracks or wires, which can be fastened to both
sides of the boat simultaneously. The maximum
purchase shall not exceed 3:1.