GTX45R is a separate PDF. Most of the LRU'S are within the main PDF. They update it so make sure you have the most current versions, or the version that applies to your equipment. I started by reading the manual. Its like 800 pages long but alot doesn't apply to your specific equipment so it goes quick. I then made a folder for every LRU that would be installed. I then printed the interconnect drawings that applied and LRU pinouts for each LRU. Took good notes on each folder. Make sure to read the diagrams and the *notes because they have pertinent info in the notes. One comes to mine is GTR200 requires 20 gauge wire unless you are running it a certain length then you step up to 18 gauge. G3X 465 you connect a pin depending on if its a MDF or PFD.

Couple tips. Label every wire, including ground using a label maker and shrink wrap. Use a main ground bus on the firewall. I would highly recommend this one. It saves tons of time and is clean.

GB24/48 B&C GROUND BLOCK 24/48-TAB FIREWALL KIT
https://www.aircraftspruce.com/catal...07-03463-6.php