Original Big Block Mount Question

[684door]

I have an original K Frame and mounts. My 383 has the two treaded holes on the drivers side to accept the mount. My question is : What size bolt , thread pitch, and bolt length (length under bolt head) are the two bolts that thread onto the block?
Thanks

 

[440 Mike]

Threads are 7/16 14 NC.

 

[684door]

Thanks 440 Mike. Any idea on length under head?

 

[440 Mike]

No idea on the length. I have a block that was drilled/tapped, but used conventional motor mounts.

 

[684door]

No problem. Thanks

 

[AndyF]

I have an original K Frame and mounts. My 383 has the two treaded holes on the drivers side to accept the mount. My question is : What size bolt , thread pitch, and bolt length (length under bolt head) are the two bolts that thread onto the block?
Thanks

Thread a bolt in there and see.