Failing that, look for a sticker on the transmission itself; sometimes there's a sticker indicating the recommended fluid.
However, common ATF types used in that era of Dodge 3500 diesel trucks include:
* ATF+4: This was a common Chrysler specification for many of their automatic transmissions. However, it's crucial to confirm this is the correct fluid for your specific transmission. Using the wrong ATF can severely damage your transmission.
* Mercon V: Some Dodge transmissions might use Mercon V, but again, this is *only* applicable if your owner's manual or transmission sticker specifies it.
Do not rely on generic ATF. Using the incorrect fluid can lead to transmission slippage, premature wear, and ultimately, costly repairs. Always consult your owner's manual or a qualified mechanic for the correct ATF for your specific vehicle.