When I was running a 231 I would keep the RPM's as low as I could. The higher up in gears I went in the tranny, the Scream for the planetaries got louder and louder at lower RPM's.
I.E. in 1st gear they were pretty quite until about 2800-3000 RPM.
2nd gear they started to get loud around 2000-2200.
3rd gear they were getting loud at around 1000-1200.
So If I needed to go faster I would shift gears and keep the RPM's low as I could. Or I would switch to HI range.
In my club in the past few years there have been a number of Tera 231 4 to 1 failures. The welds that hold the sun gear and planetaries together failed. 3 to be exact. 2 where 6 cyl guys and 1 4 cyl. Right now there might be another one going out. Under load it sometimes (getting more and more all the time) it makes a LOUD bang and pops into Neutral. The guy who owns it thinks it's a linkage issue but I think it's something more serious.
My Klune makes alot of noise too, but they don't put a RPM limit on it that I know of.
(aw12345) check your PM's