Here's my <$30 fix for the '05-'06 gas overflow problem. You can read all the background to the problem in the other threads. Long story short: '07+ got the warranty extension and NHTSA closed their investigation leaving '05-'06 owners up $#!t creek. The new TJ tank costs as much as $900 through dealers. Chrysler will "goodwill" repair them if you jump through their hoops, pay the dealer diagnosis charge, and then another $200 "co-pay". Well, they can now take their "goodwill" and their "co-pays" and stick 'em where the sun don't shine...
You can get this part new for around $30 with shipping or look up GM TSB: 04-06-04-003A for a list of vehicles to try and score one from a salvage yard.
[UPDATE: Adding this list because it's looking like we're depleting the NOS supply of these old hoses. Salvage yard hunting may have to start happening.]
2003 Chevrolet TrailBlazer with 83 L (22 Gallon) Fuel Tank (RPO NNK)
2003 GMC Envoy with 83 L (22 Gallon) Fuel Tank (RPO NNK)
2003 Oldsmobile Bravada with 83 L (22 Gallon) Fuel Tank (RPO NNK)
2002-2003 Chevrolet TrailBlazer EXT
2002-2003 GMC Envoy XL
2004 Buick Rainier
2004 Chevrolet TrailBlazer, TrailBlazer EXT
2004 GMC Envoy, Envoy XL, Envoy XUV
2004 Oldsmobile Bravada
Built Prior to December 2003
Fuel filler lower hose part #15131046:
The bulge in the middle is a little flapper valve:
Here's our lower hose that connects the filler tube to the tank: