Were the b5's and b6's THAT different? Like for example were the high note horns, p/s pump, oil pan all different?

 

Honestly, yes and no. You could probably make the horns work. Not sure if they were the same or not but they are "close" enuf. The pump will be enginne code dependant and not year dependant. There were little changes in the oil pan. The early 1.8's had different pans than the later ones but the 2.8's had the same pan regardless of 2v vs 5v.