From what I have been reading size could matter. The only warnings are against getting an element to long as it could contact something inside the water heater or the heater itself creating an unsafe condition. An element that is shorter will not pose a danger however it won't stick into the water as far, but it will still work. If it is the same voltage and wattage it will heat the same.
Jason & Wendy
2014 Ford F-350 Lariat 6.7L PSD
2015 Keystone Montana 3711FL
B&W Patriot 16K Fifth Wheel Hitch
Thanks for the responses, I asked my jack of all trades friend. He said he would need to look at it but wanted to check the element first. The old one is good. He checked all the connections and other stuff that I did not understand, so camping world here I come. It is under warranty just needed to make sure I did not mess something up. Almost wish it was the element.
2015 250 Dodge Cummings Diesel