No there are differences, quite a few.

The bottom of the dampers on the mk3 taper down to a thinner diameter where they fit into the hub and the mk3:5 dampers have the same thickness all the way down into the hub (meaning that the hubs are diffrent aswell).

Also the mk3.5 has a bigger wheel bearing (same as a mk4/5) than the mk3, but thats irrelevant to you anyway.

Bottom lines is, if its a mk3 xr2i then mk3 rs stuff will fit.