In 2010 while the GMC was on the hoist waiting for the engine to be rebuilt, I had the tanks dropped and all the fuel lines changed.

X CUT X Back home I dropped the tanks and found the fuel out line on the top of the tank had deteriorated, hard and cracked after only 4 years. The hose was SAE 30R7 with a date code of 2007.

X CUT X
I'd drop the tanks, check for rust inside and the condition of the socks. then replace the lines above the tanks too. Put new seals on the senders because the ethanol will eat that rubber too. Don't forget to replace the short filler hose pieces before they start leaking.