I contacted Peter Kassak who wrote the book "An Ordinary Day in 1945" (which is about air war events of 2 March, 1945) to see if this incident in France or the Coleman crash are discussed and they are not.
http://www.amazon.com/An-Ordinary-Da.../dp/8389450224
So I have requested from the Air Force Historical Research Agency the reports of March 1945 for both the 398th BG and the 603rd BS. These usually come on CDs (for a fee) and take a few weeks. Hopefully they will contain enough information that we can determine whether of not the Coleman loss is the correct identification. It is interesting to note that the route flown by the groups that included the 398th that day was very close to St Inglevert. The route in and out was identical while over the continent, with the first check point being Cap Gris-Nez and the 2nd check point being northern Luxembourg. (Coming out, they flew back the same way, which would very likely put them very close to St Inglevert around 1500. Hopefully the documents I have requested can clarify these things.