Brodak dope, from what I heard, is made by Randolph. Both nitrate and butyrate can be bought under the Brodak or Randolph hame. A few months ago I heard that Certified bought Randolph but I have not been able to confirm that.
The Brodak formulation might be a bit different from the Randolph/Certified product but they are compatible. I have used Randolph butyrate thinner with Brodak dope, and vice versa, with no problems. I have applied one over the other with no problems. This goes for clear as well as colors. Much cheaper to buy Randolph thinner and use it with Brodak dope.
The Brodak Crystal Clear does not appear to have much, if any, fuel resistance. I have planes with dull blemishes on them where raw fuel made contact. Although I like the fact that it is "crystal clear" and might not yellow as much over time, its fuel resistance is minimal. From the quick and dirty experiments I did, the Randolph non-tautening clear appears to have more fuel resistance than the Brodak Crystal Clear. Not that it is fuel proof, just a bit more resistant than the Brodak clear.