Any transmission I open up, is going to be done with the aid of a ATSG "Techtran" manual, along with whatever D-I-Y/consumer-oriented book(s) I can lay my hands on.
The ATSG manuals are not inexpensive, but they are a detailed wealth of knowledge.
https://www.amazon.com/ATSG-4L60E-Tr.../dp/B00Z1RFENA