400-430-455 Flexplate identification

Am trying to find a way to tell them apart. I do know that the 400/430 use the same p/n and 455 is different. I presently have 3 off engines. One is definitely off a 455 and the other, one off a 430 and one supposedly off a 455. <BR>I used to go by thickness of the teeth. The 455 one comes up at .395 inches. The other 2 measure .395 and .450 inches. The odd thing is that the one off the 430 was .395 and I had thought the 400/430 should be .450 inches.<BR>If anyone know how to tell them apart, it would be appreciated.<BR>Thanks,<BR>Mark

Hi, measured my spare from spare 430 parts and got .407" thickness, 186 teeth, and there is an X stamped on the side that would face the block, hope that helps. this is from 1968 430 from a Riv.

Scott,<BR>Thanks! From what I have been finding (also posted on V8Buick.com) it looks like the 400/430 flexplate is about .395 thick and the 455 about .450 thick. So, your numbers are correct for a 430.<BR>I took some measurements on a 455 flexplate that I know is original and it comes up at .450 inches.<BR>Apparently some flexplates got mixed up on the motors before I got them. A 455 had a 400 plate and confused the issue.<BR>I have seen the X on some of the plates too. So, I will check further.<BR>Thanks again!<BR>Mark