I am sorry, but I don’t follow what you are asking. I think you might mean the DIY flushing system.
If so the whole kit is about $40 and the T piece is made from plastic. This flushing system comes with all the
new engines. On garden flush project on our web site has a further description http://www.marinepartsexpress.com/engine_flush.html.
On the question about the including the manifolds in the a new F/W cooling kit. Volvo Penta doesn’t offer a full system which cools the manifolds as a retrofit. If you purchase the new engines you can specify a full cooling system.
Hope this helps.