I did the U-joints on the rear shaft of my 100 series. Worst part for me was removing the driveshaft. Had to borrow a friends snap on air wrench to turn the nuts.
It’s a fairly straight forward job. I can certainly help if you have the parts and a vice.
However, if you can go without the truck for a couple days, I would highly recommend removing the shaft and taking it to CSR driveshafts specialist in North Charleston. The guy there does great work and the pricing was surprising low. One of my u-joints was defective and so I had a vibration after performing the replacement. He replaced the u-joint, painted the driveshaft and balanced it for like $90. I’d imagine you could get the whole driveshaft rebuilt for a good price. All work is done with high quality parts.