1973 GMC C1500

Typical onset: 80,000-150,000 mi

Symptoms: rattling noise on cold start that disappears when warm, rough idle, difficult starting, backfiring through carburetor, loss of power at higher RPM

Fix: Timing chain, gears, and tensioner replacement requires 4-6 hours labor. Must drop oil pan or work around it depending on clearance. Original nylon-toothed cam gears deteriorate with age even at lower mileage. Replace with steel gear set and double-roller timing chain. Includes new timing cover gasket, oil pan gasket if dropped.

Estimated cost: $450-850

Symptoms: visible rust perforation in frame rails behind cab, sagging bed or body lean, cracking around spring hangers, crossmember separation, steering box mounting area deterioration

Fix: Northern and coastal trucks commonly have frame rot concentrated at rear cab mounts, spring hangers, and transmission crossmember. Minor surface rust can be treated, but structural perforation requires frame section replacement (20-40 hours) or full frame swap. Some trucks are beyond economical repair. Inspect carefully before purchase—this is the deal-breaker.

Estimated cost: $2,500-8,000

Typical onset: 70,000-120,000 mi

Symptoms: excessive play in steering wheel (more than 2 inches), wandering at highway speeds, clunking when turning, uneven tire wear, need constant correction to maintain straight line

Fix: Manual steering boxes develop internal wear; rebuild kits available but labor-intensive (3-4 hours). Idler arm, pitman arm, and tie rod ends commonly need replacement together (2-3 hours). Factory power steering boxes leak at sector shaft seal. Complete steering refresh of all components typical on unmolested trucks.

Estimated cost: $600-1,400

Symptoms: fuel smell near tank, fuel starvation under acceleration, visible rust or pinholes in tank, hard starting after sitting, sediment clogging fuel filter repeatedly

Fix: Original steel tanks rust from inside out, especially if stored with ethanol fuel. Tank replacement is 2-3 hours labor but tanks are affordable. Steel fuel lines from tank to pump rust through at frame contact points. Budget for complete fuel system overhaul on unrestored examples: tank, sending unit, lines, pump, filter. Rubber fuel lines at carb also deteriorate.

Estimated cost: $400-900

Symptoms: flooding and fuel smell, hesitation on acceleration, black smoke from exhaust, hard starting when hot, rough idle that improves with choke, fuel leaking from accelerator pump

Fix: Original carburetors need complete rebuild after decades of ethanol exposure. Internal gaskets harden, floats sink, accelerator pumps fail. Rebuild kits run 2-4 hours labor depending on carburetor type. Quadrajets are more complex but respond well to proper rebuild. Many owners convert to Edelbrock or Holley for reliability. Adjust expectations—these won't idle like EFI.

Estimated cost: $350-650

Symptoms: soft brake pedal that goes to floor, brake pull to one side, leaking fluid at wheel cylinders, seized parking brake, corroded brake lines with visible scaling

Fix: Front disc/rear drum systems suffer from seized caliper slide pins, leaking wheel cylinders, and rusted hard lines. Complete brake line replacement recommended on unrestored trucks (6-8 hours). Master cylinder often needs rebuild or replacement. Parking brake cables seize in housings. Budget for complete brake system refresh as preventive maintenance—these are 50-year-old components.

Estimated cost: $800-1,800

Typical onset: 100,000-180,000 mi

Symptoms: delayed engagement into gear, slipping during 1-2 shift, no reverse or weak reverse, leaking from pan or tailshaft, burnt transmission fluid smell

Fix: TH350 and TH400 automatics are robust but eventually need rebuild at high mileage or if abused. Common issues: worn forward clutch pack, leaking modulator, hardened seals. Rebuild takes 8-12 hours with converter. These transmissions respond well to rebuild and can last another 100k+ miles. External leaks from pan gasket and rear seal are maintenance items (1-2 hours).

Estimated cost: $1,200-2,200