Where do I get information on my Thunderbird

What parts don't match? It may have had an engine swap.

The 17 digit standardized VIN didn't come into usage until 1981. My 66 Cadillac had an eight character VIN. If your insurance company doesn't know that you need to find another one. It's unrealistic to expect a manufacturer to keep records for a 57 year old vehicle, or anything else that old. Anything could have happened in the last half century to the vehicle. Engine and transmission replacement, successful and unsuccessful repairs, you name it and this vehicle has probably been subjected to it. What you need to do is find out exactly what you have sitting under the hood. Look for casting numbers, a VIN, etc. on the engine block and heads. Look for a tag on the transmission and the rear differential. This will tell us exactly what you have and help you get parts for the vehicle. Another thing to be mindful of is aftermarket cataloging. It gets worse as the vehicle gets older. An aftermarket part number for, say a starter, may have several years and models lumped together when originally a specific part number was assigned to the starter for a specific vehicle. Most times the part will work, but sometimes it won't or it will differ in appearance slightly. I ran into this with my 1970 Pontiac Catalina in the late 90s and early 2000s. I made the mistake of buying a rebuilt carburetor from a local auto parts store. It was wrong. The original carburetor was part number 7040060. That part number breaks down as follows 704=Rochester 2 barrel Pontiac Division, 0=1970, 060= automatic transmission, Federal Emissions. That car would NOT run right with any other carburetor on it. But the aftermarket cataloging said it was the right one. The reason it was wrong was because GM used that same carburetor configuration on many makes and models throughout the 70s BUT anything after 1970 was jetted leaner to accommodate the evaporative loss emission control system which became mandatory in 1971 in all 50 States. After receiving and rejecting 6 more carburetors the store refused to even talk to me! It took me another 2 years to find the correct carburetor for that car! Guess what, it was still running great when I sold it in 2012 with the correct carburetor on it. So, the moral of the story is don't trust the aftermarket cataloging on a very old vehicle and never turn in the core until you're sure the new part fits and works correctly!! Hope that helps! Jim