Holley Carb Identification

I got this carb of a 360 that sat in a 70 Duster for like 18 years in a barn. It's old but for the price I paid for it (Free) I can't complain. I want to buy a rebuild kit for it but don't know which model it is. Maybe somebody can help while I wait for the Holley site to approve my forum membership.
The numbers on it ar
6R 3551 E
4519