Off hand does anyone know what size bolts I need from the manifold to the Y-pipes?

 

I will attempt to find the old ones to check for you, but I believe they are about 2 1/2" long, have coarse threads and have a 9/16th hex head. I bought grade 8 bolts to replace them from home depot, so its not an uncommon type of bolt.

 

Yup, 9/16 or 14mm hex head. Just put headers on mine and ended up using the original bolts cuz the cheap ones that came with the headers stripped EASY!!

 

Thanks. I attempted to do this the other day but I couldn't get an angle on any of the bolts. The back bracket has more rust than the Titanic, and laying on my back under the truck I couldn't get the manifold bolts off to save my life. Even though I used a can of PB Blaster. This weekend I have help so we are going to do a bunch of cutting to make the removal easier.