Yes you can purchase a printed manual for your 1991 Peterbilt model 379.
I went to the Peterbilt website and went straight to the facts section at
From previous experience, it is not common to find automotive manuals
on-line. I called Peterbilt directly at 1-800-4Peterbilt
I spoke to a rep in the repairs department. Unless someone else has
posted the manual online - you will have to go through a Peterbilt
dealership. However, they will be more than happy to accommodate your
request. If not, call Peterbilt and the dealerships are supposed to
order manuals at a customer?s request.
The rep also informed me that there are multiple manuals for each
truck depending on the problem.
Obviously, if it's the engine, then you will be receiving a
Caterpillar manual, etc.
Peterbilt also has a manual about the construction and maintenance of the Truck.
I would be more than happy to locate your nearest Peterbilt dealer to
price their charge for the manual you seek if you need me to. I will
only require your approximate geographic location (state/city) and
what specific problem/ manual you seek.
You can easily search for your nearest Peterbilt dealer by going to
http://www.peterbilt.com/index_dea.asp . Many of the dealerships
have their own web-site and many can be contacted by e-mail.
I apologize that I was unable to find this information easily
accessible online by download. Fortunately, the manual is still
available and accessible.