1974 PLYMOUTH DUSTER

Typical onset: 80,000-150,000 mi

Symptoms: Rough idle and hesitation on acceleration, Rattling noise from timing cover at startup, Backfiring through carburetor, difficulty starting when hot, Retarded ignition timing that won't stay adjusted

Fix: Replace timing chain, gears, and tensioner. On slant-six this is 3-4 hours with radiator in place (tight but doable). V8s are easier at 2.5-3.5 hours. Always replace the timing cover gasket and front seal while you're in there. Original single-roller chains stretch badly; upgrade to double-roller.

Estimated cost: $350-650

Symptoms: Stumbling, stalling, black smoke from tailpipe, Impossible-to-tune condition, hunting idle, Vacuum lines cracked, missing, or misrouted, EGR valve stuck open or plugged with carbon

Fix: The 1974 smog equipment (Carter BBD or Holley 1920 carbs with dozens of vacuum lines) deteriorates into chaos. Proper fix is carburetor rebuild kit, all new vacuum hoses per factory routing diagram, EGR valve cleaning/replacement, and distributor recurving. 4-6 hours if you're methodical. Many owners delete smog equipment where legal, cutting time to 2-3 hours.

Estimated cost: $400-800

Typical onset: N/A - age/rust dependent

Symptoms: Front end sitting noticeably low, uneven ride height side-to-side, Clunking over bumps from worn lower control arm bushings, Flaking rust at torsion bar hex sockets in K-member, Difficulty adjusting ride height due to seized adjusters

Fix: Torsion bar anchors rust into the crossmember on northern cars. If caught early, rebuild lower control arms (bushings, ball joints), clean and re-index torsion bars: 5-6 hours. If crossmember is rotted, you're into frame repair territory or K-member replacement (12+ hours). Upper control arm shafts seize in their mounts commonly as well.

Estimated cost: $600-1,200

Typical onset: N/A - age dependent

Symptoms: Fuel gauge reads empty or wildly inaccurate, Fuel starvation, stumbling after 1/4 tank, Visible rust perforation in tank, fuel smell in trunk, Fuel pickup sock clogged with sediment

Fix: Original 16-gallon trunk-mounted tanks rust from inside out after sitting with ethanol fuel. Sending units fail electrically or the float corrodes off. Tank replacement requires dropping spare tire, disconnecting filler neck: 2.5-3 hours. New reproduction tanks run $200-300, sending units $80-120. Always replace fuel filter and check all rubber lines.

Estimated cost: $400-650

Symptoms: Ammeter gauge pegged, burning smell from dash, Intermittent electrical failures, accessories cutting out, Melted or discolored bulkhead connector at firewall, Voltage drop, dim lights, slow cranking despite good battery

Fix: Mopar's ammeter-in-dash design routes full alternator current through the gauge and bulkhead connector. Terminals corrode, overheat, melt. The fix: bypass ammeter with voltmeter conversion and clean/solder bulkhead terminals, or install MAD Electrical bypass harness. DIY-able in 3-4 hours if you're handy with a soldering iron. Failure can cause underhood fire.

Estimated cost: $150-400

Symptoms: Visible holes in driver/passenger floor pans, Trunk floor perforated around spare tire well, Wet carpet that never dries, musty smell, Rocker panels soft or crumbling when probed

Fix: A-bodies rust in the floors, not the frame rails. Patch panels are cheap ($50-150 per side) but labor is 8-15 hours depending on extent. Requires interior removal, cutting out rot, welding in patches. Surface rust is manageable; swiss-cheese floors mean budget $1,500-3,000 at a body shop. Not safety-critical unless frame rails are gone, which is rare.

Estimated cost: $800-3,000