KY have a look at these places.
Rear upper control arm to body bushing Part #20. $14.99 USD + shipping
http://www.jeep4x4center.com/jeep-st...liberty-kj.htm
You can also search Rockauto here to find suspension for the Liberty, they have those bushes for 13.81USD
I would steer clear of Nolathane bushes on a 4x4 personally, esp in those particular bushes, with a lift in, they are always bent over at an angle, if you had a set of Nolathane ones made, you would have to have the angle set in them, not just flex them over like we do with the rubber ones. Best thing you can do to prolong their life is to get the diff drop braket from Jeepinbyal, that will go some way to correcting the static running angle of the rear upper control arm, plus, correct stress on the balljoint, and give you some adjustment of the rear pinion angle, to stop driveline vibs, and wear on the rear uni.
http://jeepinbyal.com/prod-Link_Extension-463.aspx