the bolts are suppossed to be 14mm but with so much rust they end up being like 15.2845 mm give or take lol. but really they do have to be torched off. good luck with that....i had to do mine tooJust cut them, and use some new bolts of equal grade and strength with suitable washers.
Don't you have a socket/wrench set, those can tell you what size the bolt/nut is....
trust me i tried everything to avoid running it out to the shop with hakf an exhaust hanging off ittry pb nut buster and a small breaker bar. if worst comes to worst. cut them off and get new bolts from an auto store
Word, mine look like rustknobs - so bad sockets wouldn't fit right!the bolts are suppossed to be 14mm but with so much rust they end up being like 15.2845 mm give or take lol. but really they do have to be torched off. good luck with that....i had to do mine too