Yes, they are. 1.7 and 2.0. I seem to recall that some 1.7s were not Isuzu donks.
The indirect injection 1.7 is a perfectly workable donk from my perspective. As seen powered Cavaliers through Astravans up and down the land.
The earlier 2.0 direct injection isn't intercooled - badged DT - and produces less power than the DTi (~81 versus 100 PS). Fuel consumption is comparable between the two.
It might depend on your perspective - the Isuzu donks are not as refined as more modern stuff, but are just as economical and do without the potential for common rail issues and the later 1.3 / 1.9's potential for electronic tricksies.
If you want a Vauxhall diesel from this age I suspect you're pretty much going to get an Isuzu-derived engine...
having worked on both model of engines id have to say the Isuzu engine is the strongest out of the two & had the least problems, we use to service vauxhall taxis before they were replaced with VW's & they all had the Isuzu engine fitted.
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