Of course all this discussion about the locker, but the 609 R&P is quite a bit stronger than the D60, especially in the 10 inch form (at least how I understand it). The HP10 pinion stem is 1.50”, 35 spline, but with the additional support bearing on the end. The standard Dana 60 pinion stem is 1.626”, 29 spline. And we already discussed the bearings. I’m not sure how the Super 60 stacks up. The higher hypoid angle also gives the 9” better tooth engagement.
Below is an image I stole from True Hi9. On the left is the 5.14 Hi9, which uses the 9” gear, and on the right is the D60 5.13. I don’t have a comparison photo for the HP10.
So I believe the 609 has stronger gears and the D60 has a stronger locker. I’m not sure which is more likely to fail here.
If this is all true, the 609 wins on gear strength, clearance, wheel travel, ease of setup/repair, weight, weldability, and driveline angle. The D60 wins on locker strength and cost. The outers are the same.
As I’m not overly focused on cost, I’m not sure I’m ready to ditch the 609 for a D60. The 14b would be better competition, even though it doesn’t have the benefit of reverse cut gears, but the low pinion probably puts it literally out of reach. I’m open to changing my mind, as I think I’ve shown, but not yet convinced. I’m still on board with the 14b rear.