2005, 3.8L, LS. Coolant leaked out twice, pressure tested cooling system. There are 2 plastic 90 degree thermostat by-pass tubes attached to the {R} side and under the belt tensioner with o-rings, The o-rings have failed. {Go figure, the union employee's want more money for less/half as_ work{seen a documentary on the bail-out / employee lunch time HABBITS}, the Corporate management get paid in millions, the Federal Government bails out a company that SHOULD have gone to bankruptcy court and mechanical engineers get paid a BONUS for shaving off the cost of building vehicles}. Advanced Auto sells the replacement pipes as a set for under $5.00, but customer complaints say they leak in less than 1yr. GM wants Ten dollars apiece for the pipes {can you say “approx”400% mark-up}I suggest {as much as I hate paying a 400% mark-up} buy the OEM parts, the o-rings are of better quality. NOTE; be sure to clean any o-ring / debris out of the female port before installing the new replacements.

Update from Aug 17, 2011: {"O"ring failure was due to the end of the plastic pipes breaking off at the ends of the tubes where the "O"ring grooves are} Original oem qoute was over the phone, actual price was, tube under tensioner $3.99 and tube to R-side was $12.99.} I still stand with my comment about GM mark ups due to past dealings with the dealer.