I have a 1983 Mercedes 300D turbo diesel and was wondering if anyone could tell me if it was a c-class or an e-class and if not, where i could find out.
PMack is correct, your car is part of the 123 chassis ( 1977-1985 ) group. Mercedes only had the S-Class back then ( as far as branding various models with a letter ). All other Benz vehicles were simply called a numerical number that represented the engine displacement, followed by a letter representing either a diesel engine ( D ), or a gasoline engine ( E ). Your 300D Turbo was called that name because it has a 3.0L diesel engine. If it was a S-Class, it would have been called the 300SD turbo.
It wan't either. The Mercs of that era were known by engine type, body type, and displacement. A 300D would be a midrange sedan, five cylinder 3L diesel. The "big sedan" for the year would be the 300SD, while the wagon would be the 300TD.
The small car in that era was the 190D, which actually had a 2.2L four cylinder diesel.