Gelding by Quadrangle

[austique]

I'm really looking more for a way to go about researching this. My brother owned a hunter by Quadrangle who's AHSA name was Spot due to a rather obvious spot on his belly. I'm trying to find his registered name. He is bay should have been born between 1970-1973 with 1972 being the most likely year. He did run and he was a top Regular Working Hunter ridden by Buddy Brown before we got him. Is there any sort of online AHSA record of registration I can check? Its sort of like finding a needle in a haystack