Replacing 37 year old exhaust (front pipe)

[EdJarHead]

Exhaust work is simple... just not easy, especially when you have 37 years of heat and corrosion.  Front pipe came loose from manifold much easier than expected, but those bolts/studs aren't budging yet.  Any suggestions?  Not easy access for sure.  Was hoping to only replace the front pipe as that's what failed inspection (and muffler back was replaced before I got this Comanche).  Cat is completely empty, and this vehicle is exempt from emissions inspection in Virginia, but I'd fail state inspection if I delete it.  The flange where it connects to the front pipe is badly corroded with several bolt holes nearly gone, so I may be replacing this too.  Likewise, the bracket/mount has a couple bolts/studs that have welded themselves in place.  Anyone know the part number for this?  I'll try grinding and hammering some more tomorrow, but if it's cheap and available I'll replace it before I wear myself out. 

[Eagle_SX4]

49 minutes ago, EdJarHead said:

Those studs are pressed into the manifold and are not meant to be removed. If you need to remove them and air hammer would probably be the best option.