I recently found a link for an event at the French Artillery Museum for the 2008 Saint Barbaras Event. They have two French 75mm mle/1897 horse drawn with what appears to be correct harnessing and saddles:
Unfortunately, I do not have the French harnessing and saddles myself but I do have six sets of US M1916 Harnessing and four of the six necessary M1904 McClellans for the US M1918 Limber for my French 75mm in US service: