Need more info, there is more than one vacuum line.
The transmission in a 1991 Chrysler does not have a vacuum modulator.The transmission in a 1991 Chrysler does not have a vacuum modulator.
You can find a vacuum diagram for a 1991 Ford Bronco 351 Windsor in a Chilton repair manual if the Haynes manual does not have it. You can also check with local auto stores.
Vacuum reservoirOn the left and right fender well, the one on left is cruise controll & the right is the atc
On the valve cover, with a large vacuum hose attached
junk yard
You can find a repair CD on many of the auctions. I paid $10.00 bucks for mine.
Try the dealer Parts Department, they have all the service manuals an what u need.
JUNKYARD
Go to DTAmotorsports and download you a free service manual. http://dta-motorsport.com
EBAY AND FROM THERE YOU SHOULD BE ABLE TO FIND IT WITH ALL THE LINKS ON THE WEB.
You might find this information in a factory shop manual available from AUTOBOOKSONLINE.COM.
Any auto parts store such as Auto Zone, Advance Auto, etcetera should have the part you are looking for.