As many of you probably already know, the horns and bells (and undoubtedly other things as well) are being switched around on the F40PH-3 locomotives during the rebuild process. I have been able to keep track of the horns pretty well, and the bells to an extent. The following is a listing of what units have what horns and bells, to the best of my knowledge.
100: Horn from 111 - Mixed Cast P5A; new horn put on 5/2011
102: Bell from one of the two Amtrak F40PHR's
103: Horn from 118 - New Cast P5
104: Horn from 102 - Mixed Cast P5A
107: Horn not from a Metra locomotive - New Cast P5 with #3 and #5 bells reversed
108: Horn from 116 - Mixed Cast P5A
109: Horn from 100 - Mixed Cast P5A; bell from one of the two Amtrak F40PHR's
117: Horn from 106 - Mixed Cast P5A
118: Horn from 122 - Mixed Cast P5A
119: Horn from 124 - Mixed Cast P5A
121: Horn from 125 - New Cast P5
122: Horn from 123 - New Cast P5
123: Horn from 115 - New Cast P5A; brass bell not from a Metra locomotive
124: Horn from 138??? - New Cast P5A
125: Horn from 121 - New Cast P5; bell from 127
126: Horn from 137 - New Cast P5A
128: Horn from 146 - Mixed Cast P5; horn replaced by 7/2011; bell from 130
130: Horn from 144 - Mixed Cast P5A
134: Horn from 143 - Mixed Cast P5A
137: Horn from 139 - New Cast P5A
138: Horn from 132? - New Cast P5A
139: Horn not from a Metra locomotive? - New Cast P5
144: Horn from 128 - New Cast P5
146: Horn from 130 - Mixed Cast P5A; horn replaced by 5/2011
215: Horn from 108 - New Cast P5A
216: Horn from 107 - Mixed Cast P5A
The horn that 103 went to rebuild with, a beautiful Mixed Cast P5 (the only one like it in service on Metra) has not returned, and I have pretty much given up hope. 107 returned with a P5 likely not native to Metra, as the #3 and #5 bells were reversed. The horns from 114 and 127 are also yet to return, and both of those units now have mixed cast P5A's of unknown origin.
All of the locomotives appear to have had their bells switched out (there is possibly one exception); some engines have returned with a different type of bell than when they were sent out.
Units that had brass bells before rebuild and now have steel bells: 102, 109, 125, 126, 130
Units that had steel bells before rebuild and now have brass bells: 128, 134, 138
139 left with a brass bell and returned with one as well; the pitch of its "new" bell is similar to the one it had before rebuild. That's as close as I'm willing to go to saying 139 ended up with its old bell.
The bells from units 111 and 121 have not resurfaced; 111's pre-rebuild bell sounded like it had a crac, so that one is no surprise. 121's bell was lower in pitch (almost as low as the bell on the 614), so I am a bit disappointed by that one. 127 came back with a higher-pitched steel bell, and I have no idea where that one came from.
Units 102 and 109 left with brass bells and returned with steel bells that have a slightly different tsound than the other steel bells Metra has; furthermore, I have heard such bells on Amtrak ex-F40PHR NPCU's. Thus, my conclusion that the bells on 102 and 109 are from the two ex-Amtrak units.
Of interest is the bell on engine 123. It is a brass bell, and it is definitely not from a Metra locomotive, as the pitch is lower than any of the bells on everything other than the 8200-series and old CB&Q cabcars. If 123's "new" bell did come from Metra, it would have to have come from an old cabcar.