LM134: LM134H Part and Die made by National Semiconductor?

Hi Ken, please see answers below

The lot date on the parts is 2123+5.  We are interpreting that date code as Year = 2021, Week = 23.  Is that correct?

Ans: Correct 

The part case (metal can) appears to have National Semiconductor's symbol on it (sideways Z).  Does TI still use National Semiconductors symbol for device marking?

Ans: Yes, the National Semiconductor Logo is still used on the LM134H.

Samples of these parts underwent DPAs and the die has a 134B marking on it.  Does the B designate revision B of the die and is that the correct die for the LM134H part?

Ans: Rev B is the current die revision for the LM134H.

Is this die lot a residual from a previous National Semiconductor lot?

Ans: This is a standard lot.