460 flexplate

[71HANKER]

The flexplate on my 460 was cracked and now after a trip into town it has grenaded, leaving me stranded with no gears at all. Are the flexplates year and engine specific? Or even transmission specific, i have a c6 in it. ive seen in parts catologes that some flexplates are balanced and some i guess arent. I dont know which flexplate i need. Please help i just put the truck on the road and my chevy friend is talking alot of ****. thanks dale

[Hawkrod]

Easy to tell, 79 and newer are externally balanced and 78 and older are internally balanced. From an assembled engine it is very easy to tell by looking behind the harmonic balancer. A 79 and newer engines have a large counterweight and 78 and older just have a smooth shaft between the harmonic balancer and timing cover. Hawkrod

Counterweight picture from eBay:

[71HANKER]

thank you sooo much!!! I know my 460 does not have that little counterbalance behind the harmonic balancer. So internally balanced flexplates wont have weights on them and externally balanced ones will? is that correct?

[BobbyFord]

I've heard 390 flexplates will work on 429/460's

[71HANKER]

awesome. thanks guys