Anti Freeze turned brown.

Oh no. I just did some research. It looks like I am going to have to remove the manifolds, and other things to get to the freeze plugs, and I guess there are some on the passenger side too? This is not good.
I am wondering if I can still do a good cleaning and flush without doing them.
I think you should be ok. Some of the things said here are the extreme. I only change them at work if they are leaking.