Well, time to replace both 1480 wheel joints and the three 1310 joint's on the front drive shaft. i have researched u-joints and the best one's seem to be Greasable Spicer Life Series u-joints. .
NAPA tends to only carry one brand, and it's not Spicer.
If you want extended life, it depends on what type of use? Some u-joints have enhanced strength, some enhanced sealing, and some both.
Just about all the u-joints I've ever replaced on cars, trucks, tractors, and industrial machines failed from drying out - and NOT from being overloaded. So, for them, strength is not a issue. Keeping grease in, and water out is the issue.
From all I've seen, the non-greaseable u-joints seem to last the longest - but that depends on brand. When it comes to GM trucks, I rarely see any replacement greaseable joints last as long as the OEM non-greasables the trucks first came with - with no grease fittings and retained by plastic and snap rings.
I suspect many greaseable joints get short-lived from dirt intrusion, or mixing of different types of greases from the fitting. I know that the Precision joints sold by NAPA don't have what I'd call superior sealing.
That all said, short wheel-base Blazers often have problems with premature joint failure at the rear joint caps that attach to the rear pinion. No type of joint, in itself fixes that problem. But, there are ways to fix it.
Now, if you are off-roading and using giant wheels and breaking joints , then seals are probably not your concern.