Suspension parts - Numbers?

I'm a little confused. In the parts list for 91-96 Park Avenues, the struts for both standard (soft) and sport (heavy duty) suspension have the same part number. The same with the springs, the list differentiates between firm ride spring and soft ride spring, but both have identical numbers.

What parts are actually different between the two suspension types? I think at least the struts need to be different, and most likely the springs, too.

Who can clear things up? Thanks in advance.

Anyone?

Sorry, don't know that one.

Check this link:
http://www.gm-parts-dealer.com/parts.htm
It shows 3 struts but no part #'s.
Std, HD and the electronic ones.