I have to disagree with that...
We tossed out differential bearing caps as a matter of maintinance in both sprint and drag cars and replace them with a 'Non Stressed' set about every season...
All you need is an engine hone, some Dykem or Sharpie with slash cut tip and a 1/2" drill motor...
Swap in the caps you want to use, stick the engine hone in them, and go to the local home building store to get drive extensions so you can hone the caps through the axle tubes.
(Ford 9" has removable center sections, so you can skip on the extensions if you run a Ford 9")
Coat the INSIDE of the caps/saddles with dykem or Sharpie and hone away,
When the sharpie or dykem isn't visible at the separation line anymore on either side, you are done!
Differential bearings use a HARD SHELL RACE so they don't require PERFECT FITMENTS...
As long as the separation line isn't WAY off, you will be fine with a hard shell race...
Same with compression, if the bore is 'Too Big' or seems 'Slotted' instead of round,
You can shave some off the mating surface of the cap to make the hole 'Round' again so you get the proper 'Clamp' on the bearing race...
Since this IS NOT a main or rod cap, you aren't looking for 'Bearing Crush',
You are just trying to hold a race in place that WILL NOT have any rotational torque applied to it (ROLLER BEARING, not FRICTION BEARING),
And you just need it 'Round' enough to hold the bearing race without distorting it too much...
This isn't the best picture (I'm a mechanic, not a photographer!) of the 'dimples', but you get the idea,
Just make sure you get 'Left' and 'Right' correct, or you won't have proper bearing oiling...
Not really difficult, you just need to mark the LEFT cap with one 'Dimple' at the top of the cap before you 'Salvage' it,
And you need to mark the RIGHT bearing cap with TWO DIMPLES at the top before you salvage it...
Put your 'Dimples' in the machined pad where the bolt goes so you aren't hammering on the unsupported cap area,
And make sure you remember you are only making 'Dimples' and not 'HOLES'...
You don't need to beat the crap out of the cap!
This pic shows the dimples punched into the cap at the bolt boss,
And it also shows the 'Tail' on many (but not all) of Dana Caps...
Some people use a drill to make visual 'Dimples' so they don't 'Stress' the cap.
I've done it both ways, I just don't get carried away with the hammer anymore!