This 1970 Buick GSX is one of approximately 400 GSX models produced with the Stage 1 performance package for the model year.

The optional Stage 1 performance package featured a revised cam profile, raised compression from 10.0:1 to 10.5:1, and increased output by 10 horsepower for a total of 360 horsepower and 510 lb-ft of torque.

The replacement 455ci V8 in this GSX was built using a block sourced from a 1975 Buick along with an intake manifold and cylinder heads from another 1970 GSX.

An oil change was performed in preparation for the sale.

Power is sent to the rear wheels through a replacement Muncie M22 four-speed manual transmission and a Positraction limited-slip differential with a 3.42:1 axle ratio.

Introduced to the Buick Gran Sport lineup in mid-1970, the GSX model featured a front spoiler, a rear wing, full-length side stripes, and a hood with a tachometer, dual air intakes, and wide black stripes.

This example was disassembled and underwent bodywork to being repainted in its factory shade of Saturn Yellow as part of the aforementioned multi-year refurbishment.

Additional features include a split front grille, quad headlights, and chrome bumpers and trim.

Chrome-finished 15″ Rallye wheels wear Buick center caps and are mounted with Goodyear Polyglas GT tires.

The standard Rallye Ride Control suspension features a rear stabilizer bar, a rear lower control-arm assembly, and firmer shocks and springs.

This example is equipped with power steering as well as power-assisted brakes with vented discs up front and drums out back.

The cabin features replacement front bucket seats as well as a rear bench trimmed in black vinyl with matching door panels.

Woodgrain trim accents the dash and center console.

Additional features include a Sonomatic AM radio, tinted glass, and lap belts.

The car left the factory equipped with air conditioning.

The three-spoke tilt steering wheel frames a 120-mph speedometer flanked by a Rallye clock and a combination gauge monitoring fuel level, oil pressure, and engine temperature.

The five-digit odometer shows 61k miles, true mileage is unknown.