Hooker Header install issue..

The header to trans pan clearance has nothing to do with your insulators, thick, thin, none. They would hit pan on an engine cradle! I had those on a 65/340/727 combo and everything fit, but was tight everywhere. They were a work of engineering art to snake all those equal length runners in that tight chassis...BUT mine were drilled wrong. The entire header sat about 1/4 inch off center of the ports, sat too low and could never retain the gasket as it would blow out the top. I would tighten them, then use a scissor jack on the collector and push it out until you are off the pan rail, then get yourself one of Cosgigs dual exhaust trans mount that has the cutout for the passenger side. I remember mine fit lower on that side to clear the stock crossmember. Odd that I remembered that after 14 years....clearance and dimple. No harm will be done.