You can probably ask some of the old schools that were around back when they used marching timps. I think some universities may have them as well, not necessarily for marching wise but just to have them. You may want to check out with schools and local universities and then put a search on Google or something.
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[color:"blue}CHS Front Ensemble (4 Years)[/color"]
MCL Drum and Bugle Corps(2Yrs)
[color:"red"]DCA I&E Part.(05)2nd place Keyboard[/color]
[color:"orange"]UT Martin Drumline 05-Present[/color]
[color:"blue"]West Athens Percussion (06-07)Marimba[/color]
Bruceton Central High Percussion Tech 07-Present