The only difference is the Park avenue/Ultra were available with an engine oil cooler. The part numbers are the same on models without an engine oil cooler.
I smashed my 93 3.8 v6 lesabre and radiator is bent in half so my goal is to put a new one in and since the mounting holes are already f'ed up. will the park or ultra mechanically work after i fabricate my own mounts for the front. i was looking at pictures and they even look the same. maybe they are the same??? anything
