Those arent the part numbers I have for the 5125s, so I second calling ord.
Will doI’d call Offroad Design
You bolt it to your truck and mount the shock to it instead the mount on the frame, I think. Cutting will ne needed of their bracket to get proper fit.I guess that I don't know what the extender is. Maybe it could help more than you think???? Not sure, obviously.
But I have a bad habit of modifying my trucks, so I tend to look at what can I get from different parts and try to find reasons to justify them.

Ahh, ok.
Well what if you pass on the steering stabilizer for now?
I did Ferd shock towers on my '90 to get longer shock on. It wasn't exactly quick. But you probably won't have enough flex to worry about that.... yet..
The bug takes some time to take affect...
(I am meaning the one that you can catch hanging out on here)
Maybe think about it a little and check out what you have. My '70 had enough travel with the Bilstiens with the Tuff-country springs, now that I went with ORD custom springs, they are too short. They limit up travel and droop.
Can you add the extenders later, or does that make a difference on which shocks to buy?
It can make a difference on the shocks depending on which springs and what you do with the truck.You can add them later. Extender mounts need to be drilled and the frame as well to mount it. I want to see if travel is good enough without it first.
Im not messing with the stabilizer for now.
If you do add the extender for the front, you have to order 12” travel instead of 11” for the rear. So that has to be considered if you opp to not order it initially.
I dont get why I just cant run the same size shock on all 4.
I assume its because of travel. But the travel need would probably depend on what type of off roading travel is needed or desired...