Flex Plate ID

  If the 304/360  flexplates at Napa, autozone.....ect  all have the same part number and weights, which engine is it more closely balanced for? Or are they the same?  If it would cause a vibration issue, how bad would it be?

any one have a pic of a '69 390 Flexplate ?, or is it the same as a '70?, or is it same as 343 with the weight welded on to it, if so can anyone give me the weight's weight and position ,I am taking out my 390 soon to fix the vibration which I'm sure is due to a 343 flexplate fitted,cheers

Bought the Autozone flex plate. Did'nt realize until now the 304/360 listed the same part number. Anyway , had my flywheel matched to it by a speed shop. Still has a vibration on take off. Smooths out after that. Still this is not good on the engine. I have it on a 72 360. I am guessing it may or may not be correct for the 304 either. Have searched for 321 2653 for years with no luck. AMC parts book says 73/74 360. Have one more flywheel that a lot of AMC'ERS say is correct for a 360. Will try again. If this does'nt work will decide on either buying a car with a 360 automatic and have that flywheel checked for the counter weight, or remove crank and one piston and rod and having it all balanced. I really would like to keep it a 4 speed. If you can get a known 360 flexplate a speed shop can match the balance.

yep it vibrates in neutral,car was originally a 343 but a 390 has been swapped before I bought it, just need to know if the 69 390 plate is the same as a '70 on the pic in page one of this thread or if not what size weight and placement on the 343 flexplate??

pulled the 390 and found it had the correct flexplate , though full of cracks!, it has the wrong balabcer, a  343 one instead of a 390, probably where the vibration is coming from,never mind  Ive got a good 343 to go in the car for now , the 390 has other issues so it's new owner is going rebuild it