The result are......... used a 1 1/2" socket to unscew heating element , element much shorter than expected ( about 6 inches) so had plenty of room . Element was a Camco 02142 , bought an Atwood replacement , more expensive but hopefuly better quality . Also replacing thermostats and pilot light assembly .
Damage caused by sending power to heating element with no water in tank . I suspect because of tank location it was difficult for previous owner to gain access to switch mounted on tank so he removed it. So heating element was powered up every time the power panel was turned on . I am adding a remote safety switch.
One more problem sovled !