They sell the vang parts here :
On my Wayfarer I used the 4:1 Small boat Vang, which has a proper camcleat instead of those V cleats which I don't like.
To attach to the boom most commonly something like the "RWO Heavy Duty Vang Hardware" here is used, to give you a way to quickly disconnect from the boom :
APS - Boom, Mast and Spar Bails, Straps and Tangs
Then a bail or a padeye goes at the mast.