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.