how do I know what u-joint is in the 84 c10?

[Swims350]

Can someone school me on u joints and which I have in the 84 c10, might buy a longer yoke and need to make sure it's for the right u joint. I measured and between flats on the yoke is like 2-1/2 inches. I beleive the O.D. of the caps to be 1-1/16 or maybe it's 1-1/8. It's an 85 c10 2wd short bed, all stock that I know of, except it had a long tail th350.

[Irish_Alley]

what year is it? two or three joint shaft? inside or out side lock rings? but this should be it at autozone
2-3011DG
http://www.autozone.com/autozone/parts/Duralast-Gold-U-Joint/1984-Chevrolet-C10-1-2-ton-P-U-2WD/_/N-ik2xiZ6o242?counter=1&filterByKeyWord=u+joint&fromString=search&itemIdentifier=64133_10877_1439_7892

[Swims350]

It's a 1 piece driveshaft and it's for a long tail th350 and it has the stock type u joint with injected plastic.

From what I've seen it's called 3r or saginaw 44 and uses a replacement that has inside c clips to lock it in place, I think it's 1330 style or 1310 I forget which.

[Irish_Alley]

Then you need the inside lock ring type should be the one I posted

[Swims350]

yea for the factory driveshaft, but I was wondering because I was going to get a longer yoke, but it uses a 1310 u joint and that'd mean I need a combination u-joint that be the 3r type and then the 1310 style.

Looking at other options though, like another driveshaft.

If I get another driveshaft I wonder if it'll cause problems fitting the 10 bolt flange on the rear end? I have no clue whther the one we get(driveshaft) would be injected plastic, outside locks, inside locks, not sure.