I found a reference to the "night fighter" mission for the T-6. See pdf page 87 on this link:
https://apps.dtic.mil/dtic/tr/fulltext/u2/a476873.pdf
"Bedcheck Charlie" was the name for the Polikarpov Po-2.
"It’s not well known that, in addition to our work at close air support, we had
an air-to-air mission! The enemy had a vintage, fabric-covered biplane we called
Bedcheck Charlie. He had a nasty habit of sneaking in at night and dropping
grenades on the F–86s at Kimpo, outside of Seoul. Flying low and slow, with a
low radar cross section, he was a real challenge to our air defense jets: indeed,
instead of “out-flying” the jets, Charlie “under-flew” them! The Mosquitoes
answered this challenge by slinging two .30-cal machines guns under the wings and
taking up nighttime alert at Kimpo. Of course, everyone was salivating to become
a fighter ace by shooting down Bedchecks! I drew this duty a couple of times, and,
although I didn’t have any victories, it was always a kick to taxi into the alert area
of Kimpo, park our T–6s next to these F–86s, and tell the F–86 pilot sitting on
alert there, “Okay, guys, go get a good night’s sleep. We’ll take it from here!”