Up till now, I believe most folks had agreed that one could simply swap 04 hats and springs onto the 02/03/V7 struts if you wanted.
We had installed some V7 struts with 04 STi pinks and STi hats on a WRX. The owner started to experience some knocking in the rear. We disassembled and reassembled the rear several times, only for the knocking to re-occur. Even tried jacking the rear up to see if we could get the struts to lube themselves.
While installing some pink bits I noticed that, while jacking the rear hub up, the strut assembly moved up about 1/2" into the top hat. I thought, WTH?!?! Could that be the clunk? It certainly was. Okay, we thought maybe the nut loosened itself so we tightened it down again. Knock came back almost immediately. Anyway, several weeks later I had a chance to compare an 04 rear strut with an 02 rear strut. Low and behold, the strut piston designs are different at the threaded section. The 02/03 has a bit of a shoulder while the 04 does not. The 04 also have longer threaded section. That little shoulder basically kept the 04 hat from seating completely onto the strut.
Mystery solved. Kids, don't use 04 hats and springs on 02/03 struts unless you properly modify the rear struts.
Towards the end of this thread there are several suggestions of washer fixes if you want to use 04+hats on 02/03 struts.
Here is a link to the BEST washer mod solution currently available:
Originally Posted by DomozitoLK