I cant quite tell from the pic. It should be a 25 in a 65' CJ5, it could be a 27 in a late one and ya never know what someone might have slipped in. Look for the casting numbers on the center housing. These guy's have a nice I.D. article.
https://palmbeachcustoms.com/jeep-ax...ication-chart/
The parts can get a little salty but, I am always grateful they are available. The availability of parts is one of the main reasons I restored mine.