Ouch, that hurts my eyes!
Yep, I'm pretty sure that's an Isuzu. German Engineering gone bad over in the land of the rising sun. I don't believe that much of it is compatible with the German Opels. Here is what a Kadett C GT/E looks like. Pretty similar bodies, but as opelbits has stated, completely different running gear. As I understand it, some of the basic designs are similar, but applied somewhat differently. Hmmm.... It might be interesting to pull some of the parts (such as the brake calipers and rotors) and see just how different they are. I believe that they used a 4 x 100 mm bolt pattern, but I suspect that they used NipponDenso brake gear rather than ATE (Alfred Teves) brake calipers and such.