The Espada came with a 4.0L V12 engine. It had a mid-engine layout, which was becoming popular for racing vehicles at the time. Having the engine in the center/rear of the vehicle helps with balance when moving around corners. The rear wheel drive layout meant the weight of the engine was right on top of the wheels with power, which means better overall grip on the road.
Although the majority of these were sold with manual transmission, there was an automatic transmission offered, making it one of the only factory V12 engine cars with an automatic transmission.
There were three generations of this car. They were the S1, built from 1968 to 1970, the S2, built from 1970 to 1972, and the S3, built from 1972 to 1978. From the outside they look pretty much the same, but engine improvements were made with each successive model.
Only 1217 of these cars were made, all by hand at the Lamborghini factory. Still, that number made it the most successful Lamborghini at the time.
You can find these on the collector car market and at auctions. Try looking on eBay auctions, where you'll often find at least one or two listed. Also some parts show up there on a regular basis.