Resolved.
Took many days to drop the tank as no parts came out easily.
With tank down , I cut the two fuel tank nylon fuel lines (supply 3/8, return 5/16) near the front leading edge of the fuel tank.
Then I spliced in Dorman nylon tubes ( 3/8 and a 5/16 ) that also have new quick disconnects to join the supply fuel steel line and the return steel fuel line.
Each nylon Dorman repair package was $20. I did not use their metal connectors that require heat and possibly compression fittings . I just wanted the nylon tubes with the quick 3/8 " and 5/16 " disconnects already fused to the nylon tubes.

I used Dorman shark-bite like connectors to join the new nylon tubes to the old nylon tubes that come from the fuel pump which I cut off the ends.
IIRC, each Dorman nylon shark-bite like connector package of 2 was $10.
That procedure was quick and easy. Just slid the shark-bite onto each nylon piece. Nothing to heat, nor compression fittings. Hope it does not leak fuel. Never tried these in auto repair.
This 2003 Tahoe fuel line R/R saga has been going on for 15 days and still going.

 

Watch real close for any leaks from those connections.

 

Here is a follow-up of the nylon fuel line repair with photos for the benefit of others.
The only reason that I dropped the tank was to be able to access/repair the dysfunctional fuel tank nylon quick disconnect components. Along the way, both fuel tank strap bolt/speed nuts were broken ( 2 days repair) and the fuel pump quick disconnect took 3 days to unplug. I packed grease onto the new fuel tank speed nuts/bolts to prevent moisture from ever reaching /rusting the speed nuts/bolts.