No one thread but scattered posts. My rT3 was between 21-26 naturally and rose up to the high 30s whenever I took a combo therapy including T4.
I don't know my levels at the moment. I will get labs in a month or so but there isn't an urgency. For now, I feel like a perfectly normal human so I'm not touching a thing. Whenever I play with the dose, I get symptoms again.
Last set of labs my TSH and FT4 were in the low 1's but that was on 25mcg. FT3 is much less meaningful when taking T3 because it fluctuates all day throughout the day. It's the most useful marker if not taking any thyroid hormone though.