AT Transmission Input w/ 2.7

Getting close to 190k and I've looked through all the service records before my ownership and do not see any transmission work. Just bringing this up to see what you guys recommend.. Shifts great 90% of the time but occasionally shifts hard when going into D. Should I look at getting it serviced for preventative reasons moving forward?

Also about to change the upstream O2 sensor. Better to stick with Denzo or pick one up from NAPA, Autozone or OEM replacement?

 

Obtain new transmission fluid.

Obtain FIPG for transmission fluid pan.

Obtain transmission filter.

Pretty easy to service; just make sure you get the right gasket by getting underneath and counting the correct number of bolts holding the pan.