I know there will be nay-sayers but there are 2 ways to free up those nearly frozen, dried up, front u-joints with no zerk fittings in your 4WD.
1; Take your truck to an empty parking lot, lock your front hubs, spray 1 joint with penetrating oil, make a bunch of full lock turns, do other side. Turn and spray until they quit jerking, crunching, and clacking.
2; Rip a couple strips from an old towel about a foot long, lock your front hubs, soak the rags in ATF, string them through the front joints and tie them in the back, drive with them for a day or 2. You can add oil the second day also.
This will rejuvenate dried up joints that still have grease residue in them but are still in good shape. These joints don't normally get used much and also get water in them. I have done both these methods and they both worked; saving my joints.