Truck Repair: motor rpm, throttle arm, couple questions

Question
i purchased a 1986 cumming diesel 3.9 from a bread company, it will only run 60 m.p.h. top speed up hill flat surface thought maybe the governor needs adjusted just a thought  tks. if you can help.

Answer
It has been awhile since I have seen a 3.9 4-cylinder.  I will look this up at work tonight and get back to you asap.


I cound find no information on this engine at my work.  But I would like to ask you a couple questions because this should be set up close to an older 5.9L Cummins. When you are running 60mph what is the aprox. engine RPM?  The reason I ask is; there is a stop placed behind the throttle arm on the pump, this can be adjusted inward to allow for more throttle movement.  Is this a Turbo engine or naturally aspirated?