Prior posters did good job answering based on VIN. Need data tag for possibly some more info. Need eng # to determine size and 1 or 2 carbs.

I think I can help out a little about specifics. As previously stated 4=Buick, 66=Wildcat custom, 64 would be a regular wildcat,X= Kansas City (Fairfax is a sub). the car should have... Power radio antena, AC Electric seats, power windows, Power assist brakes and steering, Tilt wheel. Option Power vaccum trunk assist, Power top. My book shows wildcat did not have posi. It is an option for the riviera. It had several motor options ... If you send me a picture of the motor I can tell you which one it is. The most popular was a 425. Here is my advise. Look on the internet for the BEST BUICK BOOK ever made for your car... It is called... 1965 BUICK CHASSIS SERVICE MANUAL ALL SERIES 1st edition. I have one for my 67 wC and it tells me every option and shows me every screw,nut and bolt used and location in taking the car apart. And what tools are needed. I bought the book on eBay for about 30.00. Great Buy. Good Luck Chuck [email protected]

Sources: Origional Factory Buick Service Manual