1970 GMC C1500

Symptoms: rattling noise from front of engine on cold start that fades as oil pressure builds, rough idle and poor performance, backfiring through carburetor, complete no-start if chain jumps timing or breaks

Fix: Replace timing chain, gears, and tensioner. Original nylon-tooth cam gears disintegrate over time. Budget 4-6 hours labor for small-blocks (250/292 I6, 307/350 V8), 5-7 hours for big-blocks (396/402/454). Use double-roller steel set, not OEM-style nylon. Water pump and front seal replacement recommended while you're in there.

Estimated cost: $600-1,200

Symptoms: visible rust holes in cab corners and rocker panels, floor pans soft or perforated under carpet, bed floor rust especially at front panel and stake pockets, daylight visible from underneath

Fix: Patch panels available but quality welding required. Expect 12-20 hours labor for cab corners and rockers, 8-15 hours for floor pans depending on extent. Bed replacement often cheaper than repair. This is bodywork, not mechanical, so costs vary wildly by shop.

Estimated cost: $1,500-5,000

Symptoms: excessive play in steering wheel (more than 2 inches), wandering on highway requiring constant correction, clunking over bumps, hard spots or binding in steering rotation

Fix: Saginaw manual steering boxes can be adjusted for preload, but worn boxes need replacement or rebuild. Tie rod ends, idler arm, and pitman arm typically worn as well. Plan on replacing entire steering linkage kit. 3-5 hours labor for complete overhaul.

Estimated cost: $500-900

Symptoms: hard starting when cold, flooding and black smoke, stumbling on acceleration, high idle that won't come down, fuel leaking from accelerator pump or bowl gaskets

Fix: Rochester 1-barrel (I6) or Quadrajet (V8) carburetors suffer from dried gaskets, stuck choke mechanisms, and worn throttle shafts after decades. Full rebuild with quality kit takes 2-4 hours. Ethanol fuel accelerates deterioration. Many owners swap to Edelbrock or Holley for reliability.

Estimated cost: $250-600

Symptoms: soft or spongy brake pedal, pedal slowly sinking to floor, brake fluid leaking at master cylinder or wheel cylinders, poor stopping power especially when hot, pulling to one side

Fix: Single-reservoir master cylinders are dangerous by modern standards—upgrade to dual-reservoir unit. Expect all four wheel cylinders to need replacement. Drums often scored and need turning or replacement. Complete brake overhaul: 4-6 hours labor. Front disc conversion kits available and recommended.

Estimated cost: $400-1,200

Symptoms: visible surface rust or perforation on frame rails, cracked or missing rubber body mount bushings, cab sitting unevenly on frame, squeaks and rattles over rough roads, doors not closing properly due to body shift

Fix: Inspect frame closely before purchase—heavy rust especially at rear spring mounts and crossmembers can be structural failure. Body mounts are 8-10 rubber biscuits that turn to dust. Replacement is straightforward but tedious: lift cab slightly at each mount point, swap bushings. 6-8 hours labor. Frame repair requires professional welding and is expensive.

Estimated cost: $300-800 for mounts; $2,000-6,000+ for frame repair

Typical onset: 80,000-150,000 mi

Symptoms: transmission fluid leaking from pan gasket or rear seal, delayed engagement when shifting into gear, slipping between gears especially 1-2 shift, no upshift or stuck in low gear, pink milky fluid indicating coolant contamination

Fix: TH350 (light-duty) and TH400 (heavy-duty) are reliable but seals dry out. Pan gasket and filter service: 2 hours. Rear seal replacement requires driveshaft removal: 3-4 hours. Full rebuild for slipping: 8-12 hours labor plus $400-800 in hard parts. Modulator valve failure common—cheap fix at 1 hour labor.

Estimated cost: $200-500 for seals/modulator; $1,200-2,200 for rebuild