When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The tank is 1-piece. There is a metal/brass reinforcing tube in the "tee". There is very little plastic around this "tee" and hose nipple. I cracked this connection when removing the hose to the heater core. I band-aided it for awhile but I bought a new tank for about $45.
got it for $59.99 and tax locally, hood up to hood down in 1 hour.
Had the same problem, just while going over and checking over the fluids, touched the hose near the front of the engine, and saw the coolant coming out under high pressure.
gmpartsdirect has it for I think $35.99 (plus tax/ship)