I read on another Olds site that the flywheel is deifferent on a 455 than a 350? Im swapping my 350 today and was planning on swapping my fly wheel from the 350 to my 455 becasue the 455 does not currently have one. Do I need to buy a 455 flywheel? Thanks for you help,

 

Nope. The flywheel is the same for 350, 1968-69 400's and all 455's. Then the 330, 1965-67 400's and 425 had a different bolt pattern for the crank to flywheel bolts. John