bolts for 93 transit exhaust?

borrowed a friends rimor camper, built on a 93 diesel transit chassis. On return journey of 160 mile round trip, exhaust became very loud. Examination revealed bolts that connect silencer? Big cylinder.. To the exhaust pipe were gone. Wondering is it just a case of fit 2 bolts and im good or is there a rubber ring or something? Could use some news guys. Ta jomo in ireland. Ps know very little about cars etc as you no doubt realise from my description