Well, ordering my cv DS. Talked the the place I am buying from and I am going with a 1310 on the transfer case side and 1330 on the axle (ford 8.8) side. I was told the 1310 is for 1/2 ton and 1330 is 3/4 ton which is stronger.
the 1330 and the 1310 have the same cap size but the 1330 has a larger cross. I have broken more 1330's then i have 1310's so unless you are going to 1350 or 1410 i wouldnt worry about it just make it work. you can get diffrent companion flanges from ford for a 1310 joint or get a conversion joint from napa.
i just did the 8.8 swap. I have my stock driveshaft to the stock Ford driveshaft flange. You can get a 1310 to 1330 U joint. I just used a stock 1977 ford index ujoint. as its the same thing... I didnt wanna have to order the spicer adapter or special u joints as if i break one id be screwed on trail.
there wouldnt probably be anything wrong with the flange, but i was missing the adapter yoke (or whatever its called) and happened to have a buddy with a yoke that fit, so i went that route. plus its easier to work with IMO. and yes it has u bolts.
If you have the option of going with either 1310 or 1330, go with 1310 for the strength over the 1330 (what I've been told and it seems to concur with post #4 but correct me if I'm wrong) and the fact that if you have a choice of running the same size u-joints on the entire rig, carry one or two spares of the same size and no matter what u-joint breaks, you have a compatible replacement.
This was the thinking behind my build with the choice to go with 1310's all the way through from front to rear.