What you can do is remove the back of the driveshaft u-joint caps and add grease to them. It'll help extend the life of the joint.
Remove the d/s at the rear, set the driveshaft on a small bucket or something ....pull off the U-joint end caps and first wipe clean the trunions. Don't drop the caps or get crud in them!! If you see any 'fluting' (lines on the trunion you can feel with your fingernail), or rust on the trunions or inside the cap needle bearings, then you might as well stop, call up the parts store, and buy/replace the u-joint, since you have the D/S off already. But if the trunion surface and end caps look 'clean', put a daub of grease in each cap. I usually try to match the grease type if I can: Blond for blond, dark for dark ...but that's me. Use what you have I guess. Also put some grease where the end-cap SEAL rides on the U-joint. Put the caps back on taking care that NO (and I mean N-O) needles shifted position and fell into the bottom of the cap as you pushed it. If you have a good head about you, you should be able to reinstall the cap w/o any problems.
Then take a C-clamp and squeeze the caps 'in' together b/c they'll be under hydraulic pressure from the new grease you put in and won't go in all the way. So tighten the caps and wiggle. The grease should relieve and the caps should be where they need to be. If they don't go in far enough, then probably a needle fell between the end of the trunion and the cap ...so remove and reposition the needles as they should be and reinstall. If the joint is drilled-through adding the extra grease should push some grease to the other caps. More than likely they're solid and then, well, at least you greased 50% of the rear joint. And also apply a little oil to the cap-seals of the remaining caps. Wiggle and articulate the U-joint/s back/fourth greatly to work (and circulate) whatever grease is in the caps you can't get to. That'll all help extend the life of the u-joint. If you do the same to the front of the d/s, it'll also help.
Since the OP lives in Maine, what often happens in the rust-belt areas, is, corrosion (rust) works it's way under the u-joint cap seal, over many yrs. When that happens moisture can get in and migrate to the needles and rust them out. So by keeping the area where the u-joint cap seals are 'oiled' that'll help stave off rust migration ...and add to the U-joint's longevity (and ultimately less repair work for the owner).
Then reinstall the driveshaft and do the same to the front driveshaft.
BTW, applying a little oil to the cap seals is a really good idea for the steering U-joint too. Good preventative maintenance thing to do.
