I know this is an older topic, but I was searching for information on a car I used to have and ran across this thread. Some of the replies says that they don't think the '66 Lesabre had a big block. It was a option.
My father was the manager of a Buick dealership in Portsmouth, VA in the early/mid sixties. All we ever had from the time I was born in 1962 through the mid '70's were a variety of Buicks. He special ordered a '66 Buick Lesabre with the "Police Package" for my grandfather, who was a doctor in a rural area of southeastern Virginia, back when doctors still made house calls at all hours of the day and night. It was a 4 door hardtop with the "Wildcat running gear". It had a 425ci motor with 340hp, Turbo 400 transmission and a positraction rearend with a 342 gear. The suspension was very heavy duty as were the brakes. Even the seats were heavy duty. It had a roll bar made into the top that you could feel under headliner. I've never seen or heard of another like it. It was passed down to me and became my first car when I got my license. What a fun sleeper car, HUGE amount of torque and surprised many a Mustang and Camaro.
Sorry I don't have any documentation for you to help you along on your quest, just wanted to confirm that there was at least ONE that existed in 1966!
