It's a three gallon tank, on all Vanagon Westfalias,  but should only be
filled to 80% of it's total capacity, about 2.8 gallons. The rest is vapor
space, where the liquid propane turns into gas, the form that the appliances
use. Overfilling can allow liquid propane to enter the stove, fridge, etc.,
very dangerous.

Always have experienced service station personnel fill the tank, and if they
fill it past 2.8 gallons, have them bleed off the excess. The auto-stop
tanks, and I believe the new ones, can't be overfilled with the new regulated
design.

Robert
1982 Westfalia