You have the 5 cylinder n/a OM617 which develops 80bhp, granted its under powered but that engine is bullet proof, like its smaller counterpart the OM616, its over engineered and under rated, that means a lifelong proposition with minimal basic maintenance. The G is geared properly and does well off road with those 80bhp. The 90s G has six cylinder 3liter turbo diesel which develops way more power.I've never owned or even driven a turbo diesel G-wagen, so I can't comment on whether the 300GD is better. But I own a 300GD (it's a 1985 LWB model 460), and without a turbo, it's very underpowered, even by Land Rover standards. This doesn't matter too much to me, but it would make it less of a pleasure as a DD.