See this link below for some information regarding resistance.
http://minimopar.knizefamily.net/ecu/ch ... mp_se.htmlRockauto (online supplier) lists part number AX4 in the Standard brand as fitting 1985 Dodge 600 2.2l turbo
http://www.rockauto.com then go thorough the pull down menus inputting the information about your car.
This ebay online listing (below) lists the AX7 for various 1985 Dodge but not the 600.
http://www.ebay.com/itm/AIR-CHARGE-TEMP ... 49&vxp=mtrThese ebay online listings (below) lists the AX4 for 1985 Dodge 600
http://www.ebay.com/itm/AX4-AIR-CHARGE- ... ec&vxp=mtrhttp://www.ebay.com/itm/Standard-Igniti ... b5&vxp=mtrThis ebay lists does not list the AX18 for 1985 Dodge 600 but for later years cars
http://www.ebay.com/itm/SMP-STANDARD-AX ... 2f&vxp=mtrI am not sure about interchangeability or whether the AX7 or AX18 can be used as a substitude. (Maybe different end connector? Maybe different electrical characteristics?) Maybe someone on the Turbo Mopar forum site could answer that question.
http://www.turbo.mopar.com I think the AX4 may now be an obsolete part.
Also See link to standard oneline catalog which lists the AX4
http://www.standardbrand.com/Online%20C ... ntent.aspxIf you look at the AX4, AX7, and AX18 photos in the standard online catalog (the three sensors all look physically different with different end mating connectors)