Looking for whatever year and model donor is a good place to start, but just a start.
The 4.10 gears could be in many other vehicles (with same size Eaton axle) or the truck you think will have them won’t necessarily.
For sure check numbers on ring gear and or count teeth to know for sure what you found.
I’ve heard of more 4:10 pumpkins coming from various other trucks than I have the fabled 70-whatever 3/4 ton.
They’re still out there, but open your search so as to not miss the easy pickings.
