[Longhorn Man]

Short answer, no.
Long answer part 1;
there's been documentation on here showing a truck with an optional overflow tank, I think it was a fleet or gov owned truck, can't remember. However, it was never listed in any factory option list on the trucks.
Long answer part 2;
There was a dealer installed, or over the counter accesory avalible through all the dealers that was an overflow tank. It looked a lot like the cheap square one you find in auto zone.