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As far as I know, the deep water exhausts were only used on USMC Avengers, so they are pretty rare.
I found this picture on the internet from a Marines museum in San Diego:
Those very short exhausts were for the Avenger air defense vehicles, so their turrets could rotate freely, as far as I know. Might have been used for other variants.
I´m pretty sure they were not used on the ambulances; those had a special version that was longer than the regular ones.