Best place to try is Ebay,but you'll pay big time,maybe try flea markets or yard sales,you just never know what may pop up!.I went to the weekly flea markets years ago for a summer and one day I got lucky,I picked a original issue unbuilt 72 'Firebird and 70 'Mercury cougar convertible for $10 dollars each! and I was at a antique car and parts show and picked up a Mpc built up 70 cuda for $15 dollars.