Particularly the coil over models?

Anybody?

The fact that they have never been cross-referenced leads me to say they are not compatible. Unfortunately, the only 911 ones I ever had were RSR fully threaded units, and I decided not to keep them because they wouldn't fit my 914. I just don't recall the specifics.

ummmmm I have 911 RSR rear shocks in my 914. I had bilstein valve them to match the springs/cprner balance info I provided.

There were no fitment issues with the 911 RSR rear shock.

I cant comment on other 911 shocks, except that most cant support a rear coil spring

Hmm. Well it was 15 years ago, and my memory is not what it was. I do remember they went to someone that really needed them. I stand corrected. However, I guess you have pointed out the true reason, normal 911 shocks cannot easily be fitted with springs.