Head Crack
 

https://cimg7.ibsrv.net/gimg/dodgefo...91a3c83177.jpg
ok, So suspected leaking head gasket, was getting white smoke sometimes, but not all the time, and had cylinder 2 misfire once, but went away after changing plug and wire. Pulled the heads and replaced head gaskets, plenum fix, distributor, rotor, ect... Anyhow, found the number 2 cylinder had a crack in it, but put it back together with new gaskets. My question is, should I source another head and replace this one, or does it look like most of the head cracks that we develop on our magnum motors? Truck runs great since the head gasket replacement, no white smoke, but I will continue to monitor the water levels as it was using water, I assume from a bad head gasket. I did do a leak down check and compression check, all were good. I heard people say that 75% of magnum motors on the road probably have a crack in the valve seat somewhere and they are running fine. Thoughts?

That crack is going to grow, and eventually cause you problems.

There are aftermarket heads that are betting castings than stock. You can get a pair for around 600 or so. Make sure the are NEW castings, and not just remans.

I think I'd wait and see at this point, since its already back together and the symptom that prompted you to remove the heads is gone. But if you want to fix it, HeyYou's advice on the replacement stands.

my 01 @ 170k miles uses a bit of water due to combustion too. used to use lots of oil prior to plenum fix. i check the water and oil regularly. don't drive it much so i don't worry about it, it runs great....but since i am keeping it forever i do see a head swap in the future. that is one mean crack though.

This is my sons truck, I think we are going to source a good head and have it ready to swap out when we have other maintenance to do, right now it is running great. I have my 5.9 apart for a rebuild and the machine shop found one small crack in the head, but was an easy fix, this one looks a little bigger.
Thanks for all of your input

Don't get factory replacement junk.
Most of the factory heads are not a good replacement.
Here is a better casting and all around better head.
https://www.ebay.com/itm/NEW-2-DODGE...IAAOSwA3dYe9hr

Anyone try these guys? Looks like fully loaded, ready to install, and no core return - and 1 year warranty.
https://www.ebay.com/itm//352410559644

Likely the exact same heads, just at a better price. Seller has a good rating, so, I wouldn't have a problem buying from them.