1968 C10 u-joints?

[1968C10Custom]

Hello!

I recently picked up a 1968 C10 Custom, originally had a 307 w/3-speed manual and overdrive, but now apparently has a 1972 Chevy pickup engine and tranny in it (350 and TH350).

I'm trying to determine exactly which model (size) universal joints are correct for this truck. The 2-piece driveshaft that is currently in the truck *might* possibly be from the donor 1972 Chevy, or might be original to the truck, I would like to know.

All three u-joints in the existing 2-piece driveshaft are identical in size to each other. The caps measure about 1-1/16" in diameter, and the end to end measurement is a little less than 3.5", maybe around 3-1/4" or so.

When I go looking online to purchase u-joints for this truck, I am met with all kinds of inconsistencies, much of the time it's being suggested that the three u-joints are not supposed to be of the same size. (?) Different part numbers are specified for center, tranny end, etc. Some vendors suggest it should be one or more of the 1-1/16" cap u-joints, others suggest it should be the 1-3/16" cap u-joints, etc. Haven't yet gotten a conclusive answer.

Can anyone set me straight on what u-joint configuration is factory stock for a 1968 C10 Custom (with original 307 V8 and 3-speed manual, with overdrive), and *also* what u-joint configuration is stock for a 1972 C10 with 350 V8 and TH350 auto trans?

Of course I can always just pull all three u-joints out of my truck and bring them down to my local Napa store and have them match what I have, but I am currently out of town and trying to get these parts ordered in advance so they'll be on my doorstep when I return. As well, I'm just simply curious as to what config is factory stock, regardless.

Lastly, anyone have a favorite brand / model u-joint? I won't be racing this truck, but I'm willing to pay extra for something that is specifically heavy-duty and long-lasting. Might be towing and/or carrying heavy loads up steep hills, etc. How about a Moog Super Strength non-greasable?

Thank you