When I was building my 37 ford , I went with Hot Rod Air and were excellent to work with .
I ordered their heat and air 3 vent unit as it was on sale plus I ordered the small billet aluminum vents , and when I opened the box they sent the next model up with the 4 vent with defrost model , and I called them and told them I received the wrong unit and no billet vents and they said it would work in my 37 and if I wanted to keep it , they would eat the loss , and they sent the 4 vents free as they called my credit card company I used to purchase the unit and credited my account of those 3 vents ( If my memory is correct they were 30 bucks apiece ) . They sure treated me well !!!