Chasing major gremlin, hope this fixes it!

UPDATE:
I noticed that the O2 sensor was on the header collector only about 12" from the end of the pipe, so I extended the exhaust it is now 24" past the O2 sensor. We'll see if that changes readings.
Pulled transmission pan. Only a little grit, no chunks.
Checked plugs. Most are normal to slightly lean. 1 on each bank is a little rich, but I have to idle back to the trailer, so this may not be accurate.
Oil filter had no chunks inside.
Compression test:
Lowest: 212 Highest 252. About a 20% difference. Average about 230.
#6 was 212, 230 with oil
#8 was 220, 230 with oil
most others didn't change much with oil, but it looks like rings are worn and it's time for a rebuild.
What do you say folks, do you agree?