I have a complete set of factory repair manuals for 71 to 73 Mustangs. Very helpful during the restoration of our 72 Mach 1. Includes Body, Interior, Electrical etc. $100
These manuals are specific to 1972, but will work in general for the other years. You may find some detail differences if your car is not a '72, particularly in the electrical sections. There are sets for '71 and '73.