hi,
there is only one grease nipple on a p6, which is on the front of the sliding propshaft. original u/j's were all sealed items. QH and HARD SPICER are still sealed. some new ones do have a grease nipple in them, but be careful when fitting them as there is a right and wrong way, the 'U' shape of the end of the shaft is narrower on one end than the other, ( can't remember which ) and if fitted wrongly the nipple will get knocked off.
ian