Should I be greasing my U joints?

I would agree with Moog had they not gone global a few years back. Here's what that means exactly. Of course as is obvious, it means they are no longer necessarily made in USA. They might be, but chances are not. Also and even worse, now they are subject to all of the reboxing that parts stores are notorious for. You may order a Moog and it will come in remarked in a "Master Pro" or some other cheap bullshit brand box. That's how they all do it now. I recommend finding a heavy duty truck parts house and getting the bonafide Dana Spicer joint. It will come in a Dana Spicer box and BE a Dana Spicer joint, with the Dana Diamond on the joint, so you know what you have. Yes, it'll cost more, but you'll get a good U joint.