Its the breather hose, it helps equalize crankcase pressure. If its leaking, the hose my be swollen and unable to seal on the snouts. You can use heater hose as a cheap replacement, or see what dealer wants for one.
'95 YJ,2.5" SL,1" BL, BFG 33's, t-body, magnaflow exh. 4 banger
All I need is more money, more space, and more time.