Rusty Fuel Pump locking Ring

I have a 2003 gmc sierra 1500 5.3 and the fuel pump went out on it and I have everything off except the locking ring on top the pump. it has rusty up there really bad and I'm having problems getting it off. Any ideas on how to get that locking ring off. Thanks

Soak it in penetrating oil, clean all the loose scale off with a brush, and try to chase the tabs around the inside of the collar with a punch and hammer - And pray.

I have been spraying PB Blaster on it for about a week now, and hitting the tabs with a punch and hammer and its still not moving. Its rusted really bad. Any more ideas. Thanks

Find an AC-Delco Lock Ring TR26, and carefully cut the old one away.

Your best shot, as Blue Bowtie suggested, is to get access to the GM Lock ring...it fits on that ring and you can use a long extension for leverage.....

But......

I have seen them so rusted, when you think the ring has broken free, it hasn't......the metal ring it locks to that is imbedded in the plastic tank sometimes moves....and then you have to get a whole new tank....good luck...