U Joint selection has me confused - 86 K10

[Orion88]

I'm swapping out axle assemblies on my 86 k10 (3.08 to 3.42) and I figured while I was at it I would replace all the U Joints on my truck. Problem is there are so many different part numbers out there for all the different applications that I no longer feel I can order them with confidence. I always use MOOG and I prefer greasable parts when they are available, but the more I look through Rockauto.com the more confused I get. Some are for the front axles, others are for the front driveshaft, others are for the front or rear driveshaft, some are this size, etc etc.

So do I even need to replace all my u joints? Truck has 101,000 miles on it and was very well maintained by the previous owner. She has seen a little time plowing snow since I've owned her but not much. I know the u joints on my front axle that I bought are worn, but I haven't checked the driveshafts yet. I know some people say you should always replace them when you replace axle assemblies, but 6 MOOG u joints would set me back a good $70 or more. So what is best practice and what are all the part numbers for my application??

[aharper33]

I have run into this as well on my 86 K20. I finally just gave up trying to figure it out and took my old one to the local parts store and had them match it up to the correct one. I didnt have time to order them and then find out they were the wrong ones.

[redneckwheelman2]

i would say forsure replace the ones in the front axle. kinda cheap insurance. since if they get to dried out and rusty they can split the axle shaft ear off. then youll need to get a new shaft and u joints. id recommend getting the spicer u joints for the front axle, there are not greasable but are sealed super well and built to last.
id wait on the driveshaft ujoints till they start to squeak or pull one of the caps off when you pull the driveshaft and see if the needles are rusty or not.

the driveshafts in my 87 have the sealed spicers which look to be originals and still have grease in them. the truck either has im guessing 189000 or 89000 miles on it. dont know if odometer has been rolled over yet.