I am swapping the motor on my wagon and knowing the fuel system has not been gone over in decades, I thought it would be wise to clean out the tank. I checked under the rear seats, I don't see any indications there is access there. Do I have to pull the tank from under the car? Is there a way to drain it without pulling the tank? Any help is greatly appreciated. Pic related - yes the headlight will be replaced.

 

Yes, drop tank from below.
There may be a drain plug, but I'll have to look at my wagon later and see.