The difference is in the strut rod diameter which passes through the strut bearing (the part with three studs that goes through your shock tower). There is a nut on the top of that strut rod either 19 or 22mm IIRC. If you change to new strut bearings that match the diameter of the strut rod you are fine and can use these strut inserts. Otherwise it won't work. Since E34 strut bearings (front) are very strudy, they rarely go bad. The front strut bearings are about $100 each new.
The rear strut bearings are much cheaper and thus should be changed when you change the rear shocks.
I hope this clears things up for you.
Mike Holbrook
Meridian, Idaho
1992 535im, 17", Euro M5 Throwing Stars 8's & 9's, FK-451 235/45s & 255/40s, M5 Sway Bars 25/20, Conforti chip, Lowes Ram Air, glass sunroof