Pay retention question

I have a question pertaining to pay retention when using return rights from a Oconus position.

Current position: GS-11, step 5

Potential future position: GS-12 step 2? Based on the two step increase on base pay that is what I come up with anyway.

If I didn’t look for a different position and exercised my return rights within the prescribed 2-5 yr window, do I get pay retention for the 12-X position I am in before leaving my Oconus position?

Let’s say I stay 2 yrs and I came in as a step 2. That would put me at a 12-4 when I leave. Looking at the 12-4 scale vs the 11-6 (what I would have progressed to had I stayed in the original position during that 2 yr time frame).

Basic pay for 12-4 is $81,884 per yr.

Basic pay for 11-6 is $72457 per yr.

With pay retention does that bring me back at 11-00 @ $81,884 basic pay? Or is there something in there about only being entitled to 50% of the difference?

Does locality pay play into the equation or is it just factored in the base pay scale?

Thank you for the information.