Just go check out your local Napa or Checkers. Make sure its for "late model chevy" application cause there are some differences between early model & late model chevy water necks. And yes, the water necks with the rubber o-ring gaskets are awesome. Mine hasn't leaked yet

Does the O-ring gasket then replace the normal gasket and sealing compound? And do you have to replace the O-ring every time you pull the water neck? Those are the biggest complaints with the stock unit (besides the fact that the front bolt is behind the fuel lines which makes it next to impossible to get at).
tia James

Yes the O-ring replaces that paper gasket so don't use it. I personally still use a thin layer of gasket maker just to be safe. The O-ring has lasted me for a couple years now & I pulled the water neck off about 3 or 4 times during that time. So far so good. I'm pretty sure any auto store sells those O-rings if you need to replace them. Just gotta check. Hope this all helps.

There is another option available which i have found very useful. A rubber gasket is available instead of the usualy cork gasket which can be used with the stock housing. This is useful because if you have an warped or damaged flange surface on your water neck, the 1\8" or so gasket will give u a leak free seal without the use of any RTV. Plus the gasket is reuseable as many times as you want. Cost about 4.69 at any parts store. Also for the mounting bolts, its a good idea to replace those especialy if u still have the stock ones on there. For one you can get something that will be easier to remove, and two, being where they are, they tend to corrode and like to break off.