Hi,
interesting, it seems as if NI decided to build a discrete push-pull transformer driver. Initially I thought, NI uses a driver from Maxim (ADI) as the datasheet of HALO TGMR340 recommends the usage of drivers by Maxim. I could not find any driver IC by Maxim with the correct pin count, hence we can rule out the usage of any highly integrated solution. The marking Q6 in the solder resist is probably correct and it is indeed a bipolar bipolar transistor / mosfet. The typical topology of a push-pull transformer driver gives some clues, that it is most likely a dual NMOS device.
The two diodes (44t marking) are BAT54SW schottky diodes by Nexperia. The two ICs (BEL marking) are 74AHCT1G08DCKRE4 by TI are AND gates.
The weird thing is, I could only find NUP4302MR6 (TVS diodes) by ONSemi for the "67" marking. That does not fit...
Both pins 1 and 4 connected to ground, which makes perfect sense for dual NMOS device (source connected to ground) in a SOT363 package like the NX3008NBKS ...