It also has 2 @ 3/8" diameter 8-18 stainless shear dowels welded on for added safety. This takes the shear load off the bolts so all the bolts need to do is provide clamping force. Uses stock driveshaft bolts, which are a high quality bolt. This doweling process requires using core differential flanges, which I have a few of in stock to help with turn around time.
I could also make them for the smaller 1310's and 1330's, but for now I'm just using 1350's. I'll be making 9 of these. They are $300 each, with your core flange provided in advance, or on an exchange basis.
I will also be making these in Aluminum after the steel ones are done. The aluminum ones are far lighter, but I also prefer to see daily driven cars that anticipate high mileage to use these steel ones due to fatigue properties of aluminum. The aluminum are stronger, but will fatigue with high stress cycle rates. Same reason you only find aluminum rods in race engines. They are lighter and stronger, but don't last as long.