Question about axles bearing

Hi guys

I´m restoring a 65 hipo 9" rearend.

Now i want to put new bearings on the axle.

But before i press the new bearings on following:

My problem is the steele plate between bearing

and the axle flange (where the bolts are pressed into).

The plate wich will be on the backingplate when putting the

rear end together later.

What surface treatment did that have? Plain Steele???

Any idea happy for any help

Thanks Jerry

Thanks Charles!

What is it called by the way? My description was a bit complicated! ha ha ha

Thank you very very much!