How many u-joints does a 91 Nissan pu have?

We have the 2piece drive shaft with a center bearing and 3 u-joints.Do I have to change the whole thing or just the center bearing?

Be sure to check ALL u-joints also! Driveshaft Support Bearing - Center $ 84.99 /ea Part Number: 7358755 Product Line: NAPA Solutions

Replace whatever is loose, has play and is worn out. You're going to be in there anyway. Why not make it all nice, new and tight? To replace: 1)Raise the rear of the truck and support the rear axle housing on jackstands. 2)Before you begin to disassemble the driveshaft components, you must first paint accurate alignment marks on the mating flangers. Do this on the rear universal joint flange, the center flange, and on the transmission flange. 3)Remove the bolts attaching the rear universal joint flange to the drive pinion flange. 4)Drop the rear section of the shaft slightly and pull the unit out of the center bearing sleeve yoke. 5)Remove the center bearing support from the crossmember. 6)Separate the transmission output flange and remove the front half of the driveshaft together with the center bearing assembly. To install: 1)Connect the output flange of the transmission to the flange on the front half of the shaft. 2)Install the center bearing support to the crossmember, but do not fully tighten the bolts. 3)Install the rear section of the shaft making sure that all mating marks are aligned. 4)Tighten all flange bolts to 29–33 ft. lbs. (39–44 Nm) on Z24i and KA24E engines; or 58–65 ft. lbs. (78–88 Nm) on VG30i and VG30E engines. 5)Tighten the center bearing support bolts to 12–16 ft. lbs. (16–22 Nm).