I hope some have been preserved!
I don't think, however, that SCL's Bicentennial unit (apparently the first locomotive to be given a special paint job, inspiring many other railroads to follow suit!) has been preserved: CSX's management apparently didn't think its historical role merited it.
When SCL decided they wanted locomotive #1776 to be pained red-white-blue with special decorations, GE had already painted one in the standard black-with-yellow-trim color scheme. So a new unit was painted in the commemorative colors, and exchanged numbers with it. I think, though I'm not sure, that the ex-1776 still in existence is the ORIGINAL 1776, not the replacement that bore the Bicentennial paint.