First Year for Cat. Converters?

[Trouper]

I just put 305 in my 1985 Scottsdale, and am having trouble finding a muffler shop that will do my exhaust work. I put in a 305 TBI, and swapped it over to carb, but wanted to leave the stock exhaust manifolds on it. (It is the 2 bolt exhaust that was on cast iron heads of the 91-93 Caprices.) I already have dual exhaust from the firewall back, but needed some pipe run from the manifolds to the pipes. Since it's an 85, and the previous owner cut off the cat, no shop will touch it unless I put a cat back on it. All I need is about 2 foot of pipe run from each manifold to the already run duals.... what is so hard about that?

So what are my options now?

By the way, what was the first year for cat's on the Chevy trucks?