Got a new Third-Member, did I F up the pinion yoke?

Ok, just found some conversion u-joints. Does stock Mustangs use 1310 or 1330 u-joints?

Typically they run 1310. The 1330 is a HD truck joint.

Visually heck out the 1350 end of the new U joint vs. your stock end. It is very easy to see why the 1350 is a much, much stronger unit. For this reason, you might consider getting a new driveshaft (and tranny yoke) that is setup entirely for the 1350 joints and have a bullet proof combination.
 
Sure does, Jerry! It's an 3.70 Detroit TrueTrac with 31-spline Strange S/S Street axles, in a Chassiswork FAB9 housing. Can't wait to get it on the road! :crazy:

Following my accident in Nov 2006 in which I ripped the axle off my car, ruining my new global west L11 Cat.5 leaf springs and new Koni Shocks, I also managed to crack the axle housing and bend the driveshaft. I used the opportunity to get a new Currie 9 inch stuffed with Strange 31 spline axels, Detroit Locker, 3.70 gears, and an alum driveshaft.

JS