There is a whole thread here about reverse engineering the various 723 variants:
https://www.eevblog.com/forum/projects/lm723-die-pictures/Google this: ua723 vs lm723 and it comes up with this from the ti support site:
LM723C and UA723 are exact same devices. The LM version was designed by National Semiconductor and UA is TI's device .
TI customer support drones are the same idiots who recommended somebody that he burns-in his UA723 chips by shorting the output to ground and running them into thermal shutdown.
Pro tip: the only thermal shutdown mechanism available in 723 chips involves release of magic smoke
All of the technical specs are similar. The only difference is in package types.
National version uses a bandgap voltage reference instead of a crappy-ass, 1960s technology Zener diode. This reference doesn't suffer from so-called "zener walkout", which is a significant early drift of reference voltage (and the reason why some people tried to bake TI's parts to stabilize them). Generally, the LM723 was found to have superior long term stability by one experimenter who bothered to test it.
On the other hand, the bandgap version has much higher noise before filtering
and this is reflected in the datasheet specs, see "Output voltage noise" with C
REF=0, but those losers apparently couldn't even be assed to compare the datasheets.
LM723 is only available in PDIP(14 through hole) and TO100 (for extended temperature range). UA723 is available in 14PDIP, 14SO and SOIC packages.
AFAIK, LM723 is no longer available in DIP. It seems they only make them in metal cans, for some last remaining aerospace or similar customers who are stuck using 723 due to the cost of re-certification of a new design and they are stuck with the NatSemi version due to aforementioned long term stability issues. So they are paying for them through their noses (look up the pricing) and TI beancounters are happy. Otherwise, this part is no longer available, you can only buy the TI version which uses a Zener diode, like the original.