For 1991, Dodge incorporated the diesel information into the main books. For 1991.5 though, Dodge did a mid year introduction of the intercooled trucks. As this information for the new IC trucks was not included in the main books, Dodge created a supplement that covered all the changes between the non intercooled and intercooled trucks. While most just think its the addition of a intercooler and some piping, there was actually hundreds of items that changed. Due to this, there is a whole manual dedicated to it.
With the help of Mopar Authentic Restoration products allowing reprints to be done, these fully licensed manuals are identical reprints to the original manuals and cover the same information, right down to the Chrysler logos.
Be sure to order the main 1991 manual if you want the full set and not just the IC supplement.
