Yes and no. The gasket does isolate the back side of the sender from the tank but the lock ring contacts both the tank and sending unit on the front.
On mine I drilled a 1/4" hole on the corner of the tank. The aftermarket tanks usually have a flange with plenty of material OUTSIDE of the weld. From there I did a braided ground strap to the frame. The original grounding strap does not work well with sending units that have larger output line.
