I'm 99% sure my front driveshaft u-joint is a 1330, but how likely is it to have a 1350 u-joint stock on a 1988 Ford E250 van?

 

What do you mean by "front" driveshaft on an E250?? Wouldn't it be 2wd if stock, and not have a front driveshaft? Or do you mean at the front (tranny) end of the driveshaft?

Honestly, your best answer to this one is to go out there and measure it. If you have a set of calipers you should be able to get all the measurements you need (or close enough) with it still in the vehicle. Ford did some weird things with u-joints as well.

 

Yeah, sorry about the confusion. I meant front end u-joint of the driveshaft. Or as you said, the tranny-end.

I measured it and it is definitely the 1310 or 1330 from the diameter of the cap. I'm 99% sure it's the 1330 because it's 3 5/8" from cap pin to cap pin.

I'm ordering a new u-joint adapter because my Gearvendor yolk is a 1310, while my stock driveshaft yoke is a 1330. Not too thrilled, but I don't have many other options.