@Fisher23 Good questions. Sounds like you are taking this seriously. Unfortunately, Toyota designed the 200 series with no dipstick. Most Toyota service advisors will tell you there’s no need to change the fluid. However, there’s a lot Cruiser experts on this forum (which I am not one) who strongly believe it’s best to change the fluid to maintain the integrity of the transmission.
Many people here will tell you to use Toyota fluid. I’m using Valvoline Full Synthetic ATF that, according to the tech people at Valvoline whom I have spoken with, exceeds the Toyota World Standard (WS) fluid. As with how I have maintained my other vehicles, after the flush I’ll do this week I will do a pan drain and refill at every other oil change. Part of our driving includes the insane Denver traffic and the 4x4 roads in the mountains. Hence, our transmission is heavily relied upon in both 4 hi and 4 low. How you drive, what you tow, the weather environment, and so on will help guide you when to change.
If your LC has at least 75k on it, I’d say flush the system.
Here are some videos to watch first.