My air handler is gurgling through the drain, this unit has NOT run in months.

This is not uncommon. Eater condenses from the Acoil and drains to the condensate pump or gravity drain. If the unit is running properly and drains, I don't think there is an issue. If it is not draining, you have a blockage in the pan drain or in the drain pipe.

Most likely your drain trap is mostly void of water since unit has not ran in months--leave ac on and allow trap to fill this should solve the gurgling noise as the trap fills with water.