From what I hear there are actualy quite a few in the lake. If they are at any kind of depth where very little light hits them they should be well preserved. I have heard of some being pulled from the great lakes and just need a good drying out to be in working condition.
Wonder if there are any Hogs down there. We could use a few more of those flying.
From my understanding. there is at least 2 (Hogs) + 58 other types still not found but listed as down in Lake Michiagan.
O'Hare airport has a nice wildcat restored after many years under the lake. (Or is it at Midway? I forget now.) That may be the one your thinking of. From my understanding it's guns and engine were in working order within a day of repairs.
EDIT: old report.
http://www.midwaysaircraft.org/training_on_the_lake2.htm2nd edit lol... 1 known F4u. "The Navy used various aircraft for these training qualifications. Through ship’s logs and Aircraft Accident Cards we know that of the aircraft listed as lost were 41 TBM/TBF Avengers, one F4U Corsair, 38 SBD Dauntless, four F6F Hellcats, 17 SNJ Texans, two SB2U Vindicators, 37 FM/F4F Wildcats and three experimental drones known as TDNs.10 Several of the aircraft used for training had prior military history. Some served in Pacific campaigns, others in North Africa. Very few were new planes. Taken individually, the aircraft lost in Lake Michigan have historical value for battle service.11 However, even though many never saw battle they are still valuable as representatives of their type, or for their rarity today. Taken as a whole, the entire assemblage is significant for their service in carrier qualifications training in Lake Michigan. This history is important to the Navy, to the states surrounding southern Lake Michigan and to the nation."
From
http://www.history.navy.mil/branches/org12-6i.htm