Is that fitting cracked? If it's not, just take the elbow fitting out and wrap some white plumbers tape (or plumber's "dope") on the threads and re-insert. Don't overtighten and crack the fitting. If it's leaking from the threads, this will cure your ill.
If the fitting IS cracked. Get it out of the tank, seal the hole, and put in another fitting.
If the tank itself is cracked, I would encourage using a plastic weld type repair. JB Weld makes a product that can go on wet.
It doesn't look to me like that leak is worth the SIGNIFICANT expense and pain for an entire tank replacement.
-2018 Greyhawk 29MV
-1997 Jeep Wrangler YJ (Toad)
-2015 Jeep Grand Cherokee Limited (Soon to be Toad)
-2014 Jay Flight 28BHBE & Ram 2500 6.4L CC 4x4 (sold)