Originally posted by C9x
"The thread size is 3/8-24"

Is that the Chevy size?

Most header bolts I run into are 3/8-16 (NC)
Or in the odd case, if they were STUDS; they would normally be 3/8-16 (NC) on the block side, and 3/8-24 (NF) on the outside. With a 3/8-24 nut.

Jay, That you? (C9x)