Heating Element recommendation in 316L stainless?

[PUDDLE JUMPER II]

HOT Water TANK rebuild:

Need a few good suggestions for a 316L Stainless a steel heating elements=

1) 12v Heating Element

2) 110v Heating Element

I need to put this bad boy back together, and can only find 304 stainless ones online... The one I removed was a rust bucket and fell apart getting the old fitting out...

Anyone have a good EURO chandlery they would recommend?

Greatly appreciate any advice folks-- it is exhausting looking for quality parts these days here in the US...

[Rapanui]

In Europe, many heating elements for boat calorifiers are 54/55mm across flats fitting which does not look like it fits your unit. They also use a magnesium anode to protect against corrosion, without that any stainless is likely to corrode.
Probably worth specifying what the fitting is to get a targeted response.