I haven't actually pulled the elements yet but the tag on the water heater shows elements rated at 3800 watts. The ones readily available at the local big box are even numbered, 3500, 4500,5500.
Can I use the 3500 watt rated elements to replace elements in this water heater?

Yep.

Like KISS said: yes you can. Only one thing I'd like to add: if you decide to install 5500 watt element in place of the original, 3500 watt element, than you have to make sure your breakers and wiring are big enough to handle the extra load.

I haven't actually pulled the elements yet but the tag on the water heater shows elements rated at 3800 watts. The ones readily available at the local big box are even numbered, 3500, 4500,5500.
Can I use the 3500 watt rated elements to replace elements in this water heater?

Yes you may. The average 40 gallon water heater comes with 45oo watt eloements that pull 19 amps. Good luck, tom