Are tach's known to be non interchangeable between diesels and gassers or is this one a dud? 1986 190D 2.5NA diesel and 1988 190E 2.3 gasser

I swapped out my tach today with one out of my parts car. Donor was a 2.3 gasser. When started, the tach jumps to full rev, rev it up and it jumps to zero. I know the range is different, but only by 1000rpm. I assumed it would work. Looked the same, plugged right in. The tach signal is (or was) good, tach has worked in the past. I replaced the tach because I broke it while working on my cluster.