Hi Gents. Im going to drop my gas tank agian so that I can switch out the fuel pump. Last time I drop it I noticed a hairline crack at the base of the filler neck. What can I do to seal up this little crack other than getting a welding job?

The reason the filler neck cracks at the base is because it really doesn't have any clearance over the frame and most Mechs don't take much care when dropping the tank and end up putting a lot of stress on the solder joint if not breaking it of completely, and to make thing worse some people have a tendency to lean on the pump handle while filling which adds stress ( I was one of those.) The new pumps don't help either as they require that the handle's rubber cup completely cover the filler neck opening in order for the pump to working - a method for improving vapor recovery. All that pushing and shoving on a stiff filler neck doesn't help.

I bought a new tank to replace my 88s' corroded one caused by a hairline crack allowing moisture to enter and rust every thing up including the intake, FPR, fuel rail, and plugging up the FP, fuel filter, and fuel lines.

The filler neck for my tank has to be purchased separately and then soldered (not welded) on.
To make mine last longer I did the following:
First, I cut the filler neck after the bend, but clear of where it passes over the frame. There's a breather 1/2" line that attached to the inside of the 2" tube, this I also cut.
I used a couple of fuel resistant coupling hoses to connect the sections back together again.
Then, I use a 2-part 3M adhesive specifically for use with harsh chemicals including gasoline.
This allows the filler neck to flex while filling because to tell the truth I still catch myself leaning on the pump handle.

As for the 1/2 breather tube, how did you seal it up after cutting it in half? Also since Im on a strict budget, I could just clean up the base of the filler neck and apply the 2-part 3M adhesive right?

Do you have a picture of your work?

I believe I do let me dig them up.

Cool. I could also just clean the base and apply that 2 part 3M right?

Yes, Just be sure there isn't already rust in the tank. Leave it out in the open to cure all day on a hot day, I guess that depends where you're at, i actually did 2 days just to be sure.

Sound like a plan. I live in the true Southern Cali. I mean deep. i live just 15 minutes north of Mexicali, Mexico. And yes, its still hot down here. There is no rust in the tank. I had just relaced the fuel tank and this will be the second time that I drop the tank in 3 months. Whats the name of the 2 part 3M?

they make tanks with the filler neck installed. less hassle. rockauto.com