Rear differential cover leaking.

I've had this truck since 2014.
A few years ago my mechanic pointed out a blob of JB weld on the rear differential cover. He welded it.

I moved recently and my new mechanic said it was leaking, and suggested I remove it and have it sandblasted and somehow sealed- I didn't catch just how.

I looked online and some outfit offers a weld on replacement, the very thought of which I find horrifying.

I'm told this part is known to be porous in this generation.
I really like this truck and have been through it in an attempt to have it outlast me. It's only got 140k miles on it.

How do you guys handle this issue?

 

I've never dealt with it but here are some threads with info. There are several repairs that appear to work.

https://www.tundras.com/search/4076783/?q=Diff+cover+rust&t=post&o=date&c[node]=2

 

I had the same problem.
Here is how I dealt with it 3 years ago at 250,000 +/- miles...
Rear diff has no rear cover, it is just thin molded steel and rusts through.
Drain out as much gear oil as you can with a hand pump.
Wire wheel all the rust off and get it to bare metal. LOTS of work.
Clean it well with brake cleaner or lacquer thinner to remove all traces of oil that leaked onto the metal.
Paint it up with POR-15. I used 3 coats.
Spray the crap out of it with undercoating spray or bed-liner spray. I prefer the bed-liner spray, seems to work better.
Refill your gear oil, and hit the road.
Not a drop leaked since, and I put over 60,000 very hard miles on it.

 

I would not sand blast the rear diff cover if it has holes in it. Wouldn't want sand in my diff. Wire wheel is legit though.