If the water jeater is aluminum, it can be welded. Ive done several. Not worth it if its corroded some.
R &R is simple, usually an 1/2 hour job each way, Welding shop less than an hour, but still $100.
Beats a new unit unless its just time anyway.
Cant weld a steel cold water heater because of the glass lining. It would rust thru quick.
If you buy that rig, choose to buy a new heater, look at tankless.