Certain muscle cars have become increasingly hard to stumble across over the years, but then some owners of American muscle are lucky enough to be the original owners of those cars, which means that unlike a lot of us they never had to “stumble across” their beloved rides.

Our featured eBay find, a pro-street Mercury Cougar out of Runnemede, New Jersey, has been with the current owner for most of it’s life. Even if not exactly original owner, the current owner of the big-block cat is pretty close, since that person has owned the ’71 Mercury since 1978.

Over a span of several years, Mercury muscle classic has undergone a series of performance tweaks. Among these includes being fitted with a full ladder bar suspension with coil over shocks, a narrowed 9″-inch rear, 31-spline axles and 4.11 Richmond gears, a conversion that was completed in 1985.

Dyno tested at 525 horses, the East Coast Cougar is powered by a 460 cubic inch big-block that was professionally built and installed in 1998. The hefty Ford mill is internally balanced and bored .030 over with forged 11:1 pistons, and the motor’s Manley stainless steel valvetrain is forced open via a solid-lifter, .625 lift, Comp cam with Dove heads and full roller rockers.

Topped by a Barry Grant, 850CFM race carburetor with an aluminum Weiand Stealth intake, the 500-plus horse Mercury chases a built C6 transmission with a 3,500 stall converter. All of these make for an award-winning pro-street that has been known in the past to run an astonishing 11.60 pass at 117 miles per hour at New Jersey’s Atco Raceway. An obscure drag racer, our featured eBay find is also a clean example of the peak of Mercury muscle. It’s different, and that’s one reason we like it!