Interesting. Curious: Why would the yellow caps be better or different than the black caps? Seems like the black caps were OEM on older Mopars and the yellow ones on the newer. Other than the color, how would the construction or gasket be different?
Hard to say what's different, the yellow caps don't seem to have that molded in "bump" for the vent but other than that they appear similar. I haven't run the yellow caps though so I haven't compared them side by side. They could have a different venting system, thicker gaskets, darn near anything. Everything Mopar is more expensive, there is a crown automotive version of those yellow caps for $9.99.
For what it's worth, the Mopar yellow caps are listed as 1995-2020 caps. The black Dorman caps I listed earlier are listed for 1978-1994. So technically for the master cylinders we're running the black caps are correct and the yellow caps are not. But like I said, I haven't tried running the yellow ones.
