Cluster fun.
Since everything I see online indicates there are supposed to be 8-10 fuses and I only have 7 slots in my fuse block.
Well that part is easy. Everything you saw is not for your car's wiring.
I am studying the manual and having a hard time understanding the wiring diagrams I also have no idea which fuse is THE fuse
Well '73 diagrams are more difficult than the early ones.
Fortunately for you, this is '73 week.
Several others have just been posting about '73s and we were just looking at that fuse box.
The '73 and new wiring diagrams have a lot of information packed in and cover various options.
We need to follow and highlight just the ones we are interested in.
This often means on computer or paper, highlighting or redrawing that circuit of interest.
The wires are all given Letter-number identifications.
First letter and number is the circuit. If that wire has a branch or a new section, it will get a letter added.
For example. R6 is alternator output wire. R6a is a branch or new section from R6.
Connectors are similarly identified. C for Connector E for Engine, I for Interior. then a number.
Before the wiring diagrams in the electrical section there is a list of what each fuse is for.