Yes. Usually the lower one. Look for rust coming out of one of the cups. There are several different designs, but as long as the replacement has the 17mm shaft on both ends, not 14mm, and it is a lower joint, not the upper one, it will interchange. If you get a used one, bring bolts and pins with it.

To change, remove the two thru bolts-13mm head, slip (read beat) the joint up the shaft until it clears the rack, then slip (beat) it down off the shaft. The upper shaft has a tab which must be aligned with the joint, which is quite visible. Slip the new one up the shaft, then align the master spline on the rack with the slot on the joint and slip it down. While you have the joint off inspect, and you will see the spline I mean. If the old joint is stiff to move, wedge a screwdriver or small chisel in the slot at the bolt holes and that should spread it enough to move a bit easier.