Many years ago I replaced the fuel tank on my ‘78 Bronco, it was leaking from rust under the straps. I bought a stock size replacement through an advertisement in one of the Auto Shopper type magazines because it was relatively inexpensive. I don’t remember what the company was called, or where it came from, but basically no issues with it. The only thing different was it had an extra hole in the top for probably some type of emissions vent that my original tank didn’t have, we just plugged that. My tank came bare steel, I painted it before we installed it. The replacement lasted quite a few years, until I quit driving the Bronco. I just reused the stock sending unit, with a new o-ring from Ford.
I have had a few original fuel tanks done through the local Gas Tank Renu in Shakopee MN, they’ve done a great job for me. They were recommended by my friend that works at a professional repair shop, they’ve used them quite a few times. Gas Tank Renu did the tanks for my ‘66 Country Squire & ‘72 Gran Torino wagon, both tanks that no one made aftermarket replacements for. Both of those tanks had small leaks that I pointed out to Gas Tank Renu, and they repaired those before coating. I had Gas Tank Renu also do the tank for my ‘67 Cougar. Even though you can easily get a new tank for the Cougar/Mustang I still had them clean & coat my original tank. It was rust free since the car came from Arizona, but had some extremely nasty vintage gas inside, and needed the thorough cleaning anyway. I reused the stock sending units in the wagon tanks, with new Ford o-rings, since they were working fine. My ‘69 T-Bird also has a tank the previous owner had cleaned & coated by Gas Tank Renu, no issues with that one either. The typical Gas Tank Renu process does coat the tank inside and outside, so just be aware the outside of the tank will come back with a black coating, and no longer have the original look. I’ve also had Gas Tank Renu do a motorcycle gas tank for me. On that one it had nice paint, but the inside was rusty & nasty. To save the original paint on that one they just did a process to clean the inside of the tank, and coated the inside with a different type of coating.
Just for informational purposes, last I checked you could still get new fuel sender o-rings from Ford for our ‘60’s & ‘70’s vehicles, most everything used the same o-ring for many years. It is a square cut o-ring. Ford part number is C0AF-9276-A. I’ve seen reports of people that have used the o-rings that come with aftermarket replacement fuel sending units having leak issues, often they can be fixed with just using the original Ford o-ring. A lot of the aftermarket replacement o-rings tend to be a round o-ring instead of the correct square cut. Your 1990 pickup probably uses a different o-ring, but it could very well still be available new from Ford, that would be where I would check first.