From 1975 the basic tub was galvanised but outer panels remained plain steel. Any model now 20 years old would show signs of corrosion unless recently restored.
Rust can affect the front wings, and these are expensive to replace; for instance, the left-hand front wing with fuel filler panel would cost £1,024 plus VAT.
The large rear wheelarch extensions of the Turbo often suffer from damage; minor dents can be repaired without using replacement panels.
Another expensive part is the rubber moulding and the rear lip of the spoiler. This has a steel insert which can corrode and distort; if needs replacing would cost £434 plus VAT, plus fitting.
Pre-984 cars are now showing signs of cylinder-head studs breaking from corrosion. A top-end overhaul by a specialist would cost around £2,500 plus VAT, including parts and labour; bottom-end only, around £820 plus VAT.
Pistons and cylinders are usually in good shape, but beware of cars with extensive modifications.
Turbochargers, if properly maintained, are reliable and have good life expectancy; there are a number of companies around who can overhaul these when the time comes. Properly maintained Turbo 3and 3.3-litre engines should achieve 100,000 miles without too much expenditure. A 12,000 mile service should cost around £400 plus VAT, plus brake pads.
Pre-89 four-speed models can exhibit poor synchromesh, especially on third gear. Clutch replacement on a 3.3 Turbo would cost around £470 plus VAT.
Early type brakes on the 3.0 are the same as on the 911 and suffer from excessive wear due to the increased weight and power of the car. The braking system of the 3.3 is much more sophisticated, though check for pads seized in the brake calipers. A common problem on earlier 3.3 models is disc wear; these cross-drilled discs are costly.
Bilstein shock absorber replacement cost around £100 per corner, depending on what setting you require. Most drivers like stiffer damping on the rear.
Check also the oil pipes which run under the sill and behind the rear wheels with a flexible hose connected onto the front oil cooler. This does corrode, causing problems.