The arrangement is left/right symmetrical in the fueslage. Only fasteners are replaced, otherwise, if there is a crack, a doubler kit is installed over the cracked bulkhead. Replacing the bulkhead itself would be a massive job. It is possible that only a left or right side were cracked, and I suppose you'd only have to install the repair kit over a cracked side, though the kit comes both sides, so you may as well install both while you have the plane apart. A 182RG I bought on behalf of a friend 7 years ago had the kit install preventatively at some time before the purchase, though it had been a US government plane, so I suppose the cost of the kit and labour were not factors!