So apparently the air in the brake system of the 1994 standard cab long bed 1500 that I just bought is coming from a hole in the main line. I tried to bleed the rear brakes, only to discover nothing coming out of the bleeder valve and eventually a puddle formed under the truck.

The line that runs down the inside of the frame rail has sprung a hole somewhere and is squirting brake fluid out on the gas tank, and then dripping under the truck.

What is my easiest option for fixing this? Could I get steel braided line made up with the right fittings and then just run a new braided line all the way back to the splitter?

Go to the parts store, pick up a 10 foot length of line the right size, a couple unions, and a flaring tool. (double flares, I do believe...) cut out the bad section of line, put flare nuts over the cut ends, flare the lines, use the unions to patch in the new piece of line you bought. Less than 20 bucks in parts, probably 40 or so for the tool... (rent it??) Then you can bleed the brakes, and expect it to work.

Do I need to drop the tank?

Nope. You can just sorta snake it thru there, and secure it as necessary. You don't want it bouncing around, it'll just break again.

Ok, so I know how to bleed the system and change pads, but that is about the extend of my brake knowledge.

You wouldn't happen to know what size line is on these trucks, and what fittings I need would you?

The steel brake line is 3/16". This link should give you an example of what type of things you will need:

I just did this on my truck. I highly recommend going with the NiCopp line. It's easy to bend by hand, easy to flare, and just works well. It's 3/16" on these trucks as stated. The line busting behind the tank is a very common issue on these trucks since they get dirty and road grime in there and you can't get it clean without dropping the tank. This was my second time having the line bust. The first time I paid a shop to do it since I didn't have time to mess with it. They just cut the line in a good section, used a union and fished the line behind the gas tank. This is the half assed way of doing it and I'm not a big fan. Because there is really no way to secure it properly behind the tank, I really don't think this one lasted as long as it should have. This time I decided to do it right. I dropped the tank, ran the new line and clipped it in all of the proper clips. I ended up going all the way from the front junction to the rear and running a single line like it should came from the factory. IMO this is really the way to do it.

That said, if you do cut the line and use unions, don't use compression fittings. Make sure you double flare the lines. All in all it's a pretty easy job. The hardest part for me was getting the skid plate brackets off before I could remove the tank. You'rs may or may not have this. I'm not sure if non offroad models did or not. It also gives you a chance to inspect the tank straps which may need replacing if you haven't already done so. Other than that, dropping the tank is a pretty easy job.

I did this twice because the first time i didn't replace enough of the line. Better than making a replacement section replace the whole line with 304 stainless steel. I got one for each of my trucks. If you do make a replacement section check that the fitting that goes on the rear brake line is long enough. The one i got didn't thread in enough and had to use the original fitting. It lasted until i replace it with stainless.

https://sstubes.com/

+1 on the stainless steel pre-made brake lines. If your funding allows, this is the easiest way to procure and replace those old steel brake lines, so you won't have to do the job twice, if you plan to keep the truck for a while.

LMC could be the store for you too check out.New addition is steel brake line kits.Spring catolog edition DE.40