Baddawg,
In the Object editor select the 88mm AAA gun.
Double click on the object name to bring up the Object properties window.
About 1/2 of the way down the properties window there are 3 fields labelled 
ID, 
Group ID and 
Object Data.
Entering a number in the field labeled 
Object Data changes the characteristics of the AAA.
From Page 10 of the documentation ( 
http://downloads.hitechcreations.com/AHEDITDOC.ZIP ) these are the values to use. 
Anti-Aircraft Objects
A Ground Gun is the object type for antiaircraft gun.  The value of Object Data determines what type of gun it is.  Object Data (0) is a 20MM Gun.  Object Data (1) is a 20MM Quad Gun.  Object Data (2) is a 37/40MM Gun.  Object Data (3) is an 88MMX Gun.   Object Data (4) is a light machine gun.  Object Data (5) is a heavy machine gun.
Spotcha in the Air