If I cut the flange bolts and converter bolts off(which I am going to have to do because there aint no threads on them) where do I get new ones at and are they special bolts?

 

One Thing I've found, and it may not be relevant here but I'll pipe up anyway, is that pneumatic impact wrenches break the rust welding and spin these bolts right off without breaking them or stripping the threads. Just thought I'd interject.

 

I agree but I can not reuse these bolts even if I get them off...they are half the size they used to be on the part that sticks out past the nuts. I also can not get my impact socket on the ones on the rear Y pipe flange these must be the original salt weathered bolts.