Seems like we're eaten up with damper questions lately, this is the third time in just a few days I have referred to the Damper Doctor site. Krfrea, this chart indicates that at least 3 different dampers were used on a 350 '70-'76. Call these guys and see if they can steer you in the right direction...
http://www.damperdoctor.com/Merchant...egory_Code=CHE