I think the process would be a bit more complicated. I don't know how things work on earlier diesels, but from what ive read, my 92 300E has a pretty whacko climate control. It is all computer linked and changes air ratios according to speed etc. So I don't think you could just pop in another unit, you would have to rewire everything related to the AC in the car, and I think that would take weeks. But, I don't know what the AC system is like on your cars, it might be simpler....