Zip,
Apparently, there was a changeover from one style of axle flanges to another style. See this link for additional help.
http://2phast.com/190E/lsd.htm
It will be up to you (or someone else on this forum) to determine the breakoff point between the two styles. By the way, just ignore the fact that the guy in the link is installing an LSD differential. They key is the year of the axle.
Edit: Sorry, senior moment was in progress. The axle flanges will be interchangeable. While the diffs are out of the car, put them on the bench. Open them up and remove the C clips that retain the flanges inside the diff. Do this on both the new and old diff. Exchange flanges and mount the new diff with the old flanges. This is literally a 10 minute job if the diffs are on the bench.
Good luck,
Tom