Gas tank leaks is rusted inside and out am looking for a replacement tank

There are several possibilities and I would not park the vehicle inside. You could have a rusted gas tank, rusted gas lines, leaking fuel filter(Fram had a recall) and this is just leading up to the hood.
Under the hood, the fuel rail, injector O rings, can also leak.
You need someone to physically check your car. You should probably tow it to a repair place if you do not think you can fix it yourself.
About the most expensive repair would be to replace the gas tank. Any of the other parts would be cheaper- some $10-$50 per piece.
This is just something that needs to be seen to fix.

No.
Replace tank.
Buy 40 gallon from local Lowes and install yourself.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Under thin metal shell is a welded steel tank, surrounded by insulation and then covered with painted metal shell. The shell is what you look at.
The inside steel tank is made to withstand high pressure expansion that comes with heating water.
The steel tank has rusted out.
Turn gas control valve to vacation, so pilot light stays on, and then only heat enough water as needed until you can replace tank.

Prevent next tank from rusting by replacing anode rod, and ground water pipes.
http://waterheatertimer.org/How-to-maintain-water-heater.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Copy following link for troubleshoot resources:
http://waterheatertimer.org/Leaking-water-heater.html

Replace rusted tank
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Prevent rusted tank.
If nipples are leaking, and they did not leak before, then tank has most likely rusted out and needs replacement.
Cause for rusted tank is depleted anode rod.
Inspect and replace anode each 1-3 years.
http://waterheatertimer.org/Replace-anode-rod.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

1. remove the hose from the carb and see if the petcock is shutting off the gas and if not clean, repair or replace the petcock.
2. look in the tank and see if it has rust in the tank even a small haze of rust as rust will cause the needle and seat to stick in the carb and make the gas leak. If the gas tank has a lot of rust it may need a tank rubber liner kit added or even a new tank to stop the leaking.
3. if the bike has been sitting for a while it may have trash in the fuel system(carb/petcock/tank). Rust or any trash can cause a leak. Properly clean out the carb and fuel system and add a new filter when done.
4. Improperly adjusted or bad needle/seat or float in the carb will cause continual leaking. Replace the needle/seat/float and adjust the new one when installed. Check your service manual for float adjustments.

There are some products which will repair a fuel tank. It depends on the leak.

Some of the products require removing the tank, adding the leak chemical and swirling the mixture inside the tank. Other products are like JB Weld which could work, but there are specific chemicals just for this job.

If you have rust on a 1999 vehicle, it can cost you less to replace the tank new, than to buy chemicals and lose gas when they do not work. Rust is especially hard to guarantee a repair on. Fix one place and another leaks a day later.

Check out the Internet for new tanks. It will be harder to find an old tank because most are ripped off before the Salvage cars are allowed on the lots.

Radiator shops sometimes do this repair.

I hope my solution is helpful.

Replace water heater, before it leaks on the floor
Rusted out inside

If you'r really lucky you may find a leaking fitting on top of the water heater thats draining down inside the shell and out the bottom, otherwise its time to replace a rusted out water heater.
Sorry

if you bought new tank everything should be included if not remove them from old tank and replace

Sounds like the fuel pump. Its located inside the fuel tank so it would make sense that it only leaks when the truck is running. Hope this answers your question. Best of luck.
Greg

sounds like you are going to have to drop the tank out to inspect and fix. with luck it will be leaking from the fuel pump seal or the return line.
Bad luck would be if the tank is rusted out and needs to be replaced.
Syphon as much gas out of the tank as you can before you drop it , gas is heavy.