There is a yard off I-5 north of Sacramento, CA that has many C-bodies I was told (never been). A filler neck would be cheap to mail and a CA one should be rust-free. A yard north of Phoenix (Black Rock Canyon?) had many C-bodies (pricing can be aggressive). But, that new one at Vans is only $70. If like my Newport, there is no vent tube at the rear filler neck (unlike A bodies). I recently replaced the fuel tank w/ a CR9 (for ~1968 B-body) and fit fine as others posted. I recall a vent tube connects at the front of the tank. I ran a new 3/8" fuel tube and used the original 5/16" tube for return, thru a 1/4" vent tube in the new sender. That is so I can used EFI.