Annicorvette, Thanks for the info. from the article about fuel tank repairs.  Appreciate it!  We did get our tank out and realized the leak was not the fuel tank but just one of the lines.  We are replacing the gasket and other things while we have it out (as suggested).  Should be back on the road soon as the parts arrived today!

I was of the impression that the 77 does not have a "bladder",just the rubber neck around the gas cap area. If it has a bladder,would that be an entire tank liner?

If you go with a new tank take Joels (Adams Apple) advice and seal it with POR's tank sealant. That will eliminate any rust problems in the future. I even have PORed the outside of tanks with POR-15(great stuff) and while it was setting up(still tacky) I painted it with chassis black paint to help prevent the ultra violet light(sunlight)degrading POR-15 is supsetable to.It sets up hard,is flexable,acid proof. Just be neat with POR-15 cause it will bond to anything it touches and stay there( hands, clothes, floor ect). I have a set of Jeans that have been dripped on from three years ago. Only buy what you are going to use. After you open it up it will start to harden. Even after putting the lid back on. I dont open the can lid but punch a small hole with a nail 180 degrees apart and drizzle out on the brush what you will be using.It lays out very nicely even with a brush. Then quickly put in a screw or tape the hole over to seal it.It will start to harden(in the can) fast. Best stuf I've ever used though.