Jesper Schwartz spent a lot of time in his garage in Sweden converting his 1974 Saab 99 X7 into a RWD track car. It starts with a turbocharged 2.3 L Saab B234 inline-four making 360 horsepower and 480 Nm (354 lb-ft) to wheels on 1.5 bar (21.7 psi) of boost from a TD04-19T turbocharger. The engine is fed 98 RON fuel through RC 750 cc injectors from a Bosch 044 pump and 40 L fuel cell. Jesper’s custom RWD drivetrain uses an Opel R25/28 five-speed manual transmission with a Saab 9-5 flywheel, Sachs pressure plate, and 4-puck sintered clutch, modified two-piece driveshaft, and Ford 7.5-inch rear end with LSD. The car’s front suspension features boxed upper control arms, Saab 900 front spindles and modified hubs (5×112) while the rear suspension was taken from a 1996 Ford Scorpio sedan and uses GAZ adjustable coilovers. You can view more photos of the project and how it was built in the build thread.
Source: GarageT (project page), @schwrtzwrks, and Dyno Channel