Hi
I take its one of the larger Xtreame jobs? lets get the conversation going as after 5 posts u will be able to post a few pics..
what size hole is it? and what are you planning for filtering the mash, A fb, or a manifold or mesh attachment inside?
if your looking at a manifold or mesh which needs a connection on the inside too then its a case of fitting something thru the hole to provide both side connections.
the popular choice is a drilled or filled through 15mm compression tank connector, but as u already have a drain hole that may not be best.
is the hole you have threaded?