To set the record straight...
 

Hello Folks: Before I replaced the shocks on my '89 hatchback I searched through this forum about using '99 and later Stang shocks on Fox cars, the opinions are diversified. Well, I've done it, and here's what I found:

The shocks are a perfect fit;
The struts will fit but they are about an inch longer than Fox struts. I called various places (mustang parts specialty included) to confirm this.

However I think it's possible to modify the struts and make it fit. You will have to extend the threaded top portion an inch, I don't know how easy this can be done in a machine shop, chances are it's not worth the hassle.

In case some other Stangers out there as poor as me...

Hmmm... I have the struts on my car right now. 87GT. They have seen no modification. They just sit an inch further into the travel.

No big deal.