All '93 diesel models will have a Tdi engine, apart from ex-military vehicles which will be a 2.5 NA (naturally asthmatic) diesel engine which is basically the same as the old series engines. The Tdi should be a 200 series, but if you're buying from the UK there's a look out for the later 300 engine retro fitted.
Personally I'd choose a factory 200 over a retro fit 300 every time - at least you know where you stand with LR's fitting, rather than Joe Friendly and his mate working on his front lawn at midnight smashed out of his mind
Other than that they're standard fare for a defender.