Later 100/A6 (typC4) dashboard into early 200 typ 44

[Gerard]

Ti is right. There's electrics to be considered. I've only had 
experience on the later spec'd type-44 (mostly because my dad would not 
let me dismantle his 87 100 :D), but I'd venture to say you're gonna be 
looking at some funny wiring for a while. The wiring for the aircon for 
example, and you'd more likely than not have to get extra little things 
like the proper speedometer sender units because one is electronic the 
other is cable. The old 87 100 auto was cable driven, but my '90 200 had 
electronics.

The thought of the electrics is what scares me more than swapping the 
interiors.