These are a GOOD deal... The Haynes Manual...
If I remember correctly, has an ADDENDUM of sorts in the back for the later models... and its GOOD, but the IAP SHOP MANUAL will make things clearer, easier and better.
The Hayne's alone is GREAT for '75 - '78 models and GOOD for '79 and '80. For some reason I don't believe they mention or separate the '74 model in the photos and text... so its something to be aware of.
Good price for both as well... NEWBIES take note if you don't have one.