Story
1964 Studebaker Avanti R3
The R3 was the rarest factory-built Studebaker Avanti configuration. Andy Granatelli's Paxton team enlarged the Studebaker V-8 to 304.5 cubic inches, added special heads and a hotter cam, and fed a Carter four-barrel inside a pressure box with a Paxton centrifugal supercharger. Studebaker assembled only nine customer-production R3 Avantis.
Nine factory cars
The nine documented cars are R5089, R5237, R5394, R5532, R5546, R5593, R5625, R5642, and R5643. The first five were built with four-speed manuals; the final four used the Powershift automatic. R5643 was the last Studebaker-built Avanti, completed in December 1963 as a white R3.
That nine-car list is the first authentication test. Paxton later sold additional R3 engines, and owners have converted R1 and R2 Avantis to R3 specification. Those cars can be technically fascinating, but an R3 engine or pressure box does not turn another serial number into one of the nine factory R3 Avantis.
What changed
The R3 used larger valves, special heads, forged flat-top pistons, heavy-duty bearings, a hotter camshaft, tuned intake ports, custom exhaust headers, and Prestolite transistor ignition. Factory references commonly rate the customer version at 335 gross horsepower and 320 lb-ft; high-output pulley and valve-spring combinations account for the often-repeated 400-horsepower figure.
R3 cars also received a larger Dana 44 rear axle with flanged shafts, heavier front springs, strengthened control-arm bushings, and body shimming for pressure-box clearance. Power-assisted Bendix/Dunlop front discs and rear drums remained the Avanti braking arrangement.
Appearance and cabin
An R3 did not rely on loud exterior decoration. It shared the 1964 Avanti's fiberglass coupe body, mostly square headlamp enclosures, full wheel covers, and seven-color palette. Inside, the clearest R3-specific visual is the 8,000-rpm tachometer. Most 1964 cars used mono-color pleated Regal vinyl, black carpet, and woodgrain instrument and console panels.
What to verify
Start with one of the nine serial numbers and obtain its Studebaker production order from the Studebaker National Museum. Then compare the R3 engine prefix and assembly stamp, red engine finish, natural-metal pressure box, special heads and intake, ignition, transmission, Dana axle, chassis changes, paint, and interior with the order and dated components. A production order plus a coherent car is much stronger evidence than badges, an engine swap, or a later restoration alone.