This may not go here, but since it is specifically related to the 300ZX, maybe it does.
Common Problems (http://www.zeeyalater.net/comprob1.htm#tail%20lights)

hmm..excellent informative post soaring.

Like what? Timing Belt? When should it be replaced? I'm looking to buy a 300 ZX...anything I should watch out for?

this link should prove to be helpful...it kind of blends in with soarings post..

http://www.zeeyalater.net/comprob1.htm#tail%20lights

Many things to look for on the TT.. leaks under the car Turbos ? Smoke from engine or turbos,,,? Last time the timing belt was replaced. Old vaccum hoses are the worst.. Boost leaks everywhere...

TXQ45

well, with any turbocharger when the internal seals go bad, it will leak oil which causes smoke.