For some reason, I thought one of the other colors was a tan. Maybe it's because I've got a photo of a Strathcona's Centurion in a sort of tan camo scheme in Sennelager. (I'll have to dig the photo out.) It just goes to show how unreliable memory is after a half century.
Strangely, in spite of being an avid photographer during my years in the Army, i don't think there are any photos in my collection showing camouflaged M113s. There are a few pictures of the platoon/company tracks, but they're in factory OD. ( Dan, we obviously did not consider leaving a record for history back then.)

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However, I do vividly remember that the paint used was drab or matt. It wasn't glossy. I also remember that we covered the factory OD color completely, perhaps because it was a semi-gloss and not a true drab paint.
And, Michael, we often ran the tracks without the rubber fording baffles or shields (as shown in the above photo) on the treads. We only attached them when we were swimming the tracks. We also made sure that the drain plugs were screwed in tight when we were swimming them!
Thanks, Michael.