Sending unit leak - gasket question

last year for the woodward cruise I had to replace the gas tank on my friends challenger AND his charger. i ended up using (after wire brushing and cleaning up) the old sealing/locking ring because the new ones are just too thing to seal correctly. no sealant required. if you wanted to bend your tank locking tangs you MIGHT be able to get the new ring to work but I would not try it. no leaks after using the old locking rings and he said it hasn't leaked or left spots on his new garage floor.:D