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1975 Plymouth Road Runner
The 1975 Road Runner was a one-year B-body design built on Plymouth's new intermediate Fury shell. It remained its own Road Runner model rather than a Fury trim package. The RM21 two-door hardtop combined a blacked-out grille, bird identification, up-and-over body and roof stripes, a deck-lid stripe, heavy-duty suspension, front disc brakes, and Road Runner cabin trim.
Six documented engine paths
The U.S. dealer data book lists the E44 318 two-barrel as standard. Optional engines were the federal E57 360 two-barrel, California E58 360 four-barrel, federal E63 400 two-barrel, E64 400 four-barrel, and late-introduction federal E68 400 four-barrel high-performance engine. The exact rating and exhaust layout changed with emissions application, so engine code, market, induction, emissions hardware, exhaust, transmission, axle, dates, and records must be read together.
Manual or TorqueFlite
The 318 used a column-shifted, fully synchronized three-speed manual as its standard U.S. transmission. TorqueFlite was optional with the 318 and required with the larger engines. A floor console required bucket seats and the console-shift TorqueFlite. Canadian literature describes TorqueFlite as standard, so the selling market and factory paperwork matter before describing one car's original controls.
Heavy-duty B-body chassis
Every Road Runner received heavy-duty torsion-bar front and leaf-spring rear suspension, front and rear anti-sway bars, front discs, and rear drums. The U.S. data book lists 8.25- or 9.25-inch rear axles and 2.45, 2.71, 2.94, and 3.21 ratios by engine and transmission, with Sure-Grip choices. Power brakes were required with the 360 and 400 engines; power steering and heavy-duty shocks remained configuration-specific.
Trim, production, and proof
Factory literature documents bucket and split-back bench paths, Sundance cloth-and-vinyl trim, a console, tachometer, Tuff wheel, vinyl roofs, Rallye and road wheels, a performance hood treatment, and the optional deck-lid tunnel stripe. A secondary production table reports 7,183 Road Runners, and a valuation guide reports a $3,973 base price, but no reviewed factory ledger divides that total by drivetrain, axle, paint, stripe, trim, option, plant, market, date, or surviving-car status. Begin authentication with RM21 identity, then reconcile the full VIN, fender tag, broadcast sheet, body stampings, drivetrain, chassis, finish, cabin, dates, and ownership history.