Give the fine folks at Tom Wood's Custom Driveshafts a call I've been using Tom's driveshafts for something like 16 years now and I think I'm probably on my 6th TW driveshaft by now. Tell them you want sealed Spicer 5-1310x u-joints which are an extra-durable problem-free and stronger u-joint for the OE Spicers that are in your driveshafts now. No need to grease them either, they're a great u-joint for the driveshaft.
www.4xshaft.com
If Tom is there, ask to talk with him for your order and please tell him I said hello. He's absolutely the nicest most patient gentleman I've ever met. No one surpasses the pre and post-sales support there. You don't need to know anything about it, they'll walk you through the process and you'll have your new driveshaft in just a couple days.