I have a 65 mustang with a 351w and the stock 289 exhaust manifolds. I purchased Hedman Header #88660 which is the full length version of the swap headers. The whole exhaust was to be replaced, so I took it to an exhaust shop here in Austin to be built. They just called and said that the headers would not fit due to head-to-shock tower clearance. It sounded like they just measured the area instead of actually fitting the header to the motor. The stock manifolds fit snugly but work, and there are monte carlo bars installed to prevent shock tower sag, so I'm not sure what the problem could be. So my question is: since this is a common swap and I haven't seen any posts where people have had problems with it, should I assume it does work and that the muffler shop is being lazy, or am I missing something important. I'd just like to have a better idea if they can fit before I pull off all the exhaust. Does anyone have any experience with this? Thank you for any help.