No problem. Yes, the hole is in the back wall of the T8 and the probe is in the back. I use the entire T8 (no divider) and my probe is on the cool side. It's about 12" away from the sidewall on the cool side. With a divider, you'll probably want it closer to your sidewall.
As a side note, I did have it on the hot side at one time, but I found this seemed to adversely affect my Herpstat controls - it would either run at close to 100% or 0%. This caused high temp spikes. With the probe on the cool side, the Herpstat seems to be able to maintain the temp in a more constant range.
Sent from my iPhone using Tapatalk