This is what i have been told regarding my transmission and the chrysler truck transmissions. In 1994 is when they made the transmissions in the ram trucks more electronically controlled, with the lock up converters that could go in and out of lock up with a speed or rpm sensor, chrysler realized these newer lock up transmissions the 46re mainly was creating alot more heat then the dexronIII fluid could handle, therefore transmissions mainly the 46re's were becoming known for burning up the converter clutches, so thats when chrysler developed the atf+ 7176 fluid, and in 2001 they made the +4 fluid for longer drain intervals and better heat protection.
Dodge did not have an overdrive transmission in the ram trucks untill 1989, in 1989 they came out with A-518 for the ram and cummins trucks and the A-500s for the dakota trucks.
From 1989-1993 they used dexronIII as factory fill, and sum of the gas rams came with lock up converters but not all my 1991 is a factory non lock up A-518 and it is hydrailically controlled, the only thing electric about it is the overdrive.
So what i have been told is thatif a person owns a 89-93 dodge ram truck it is totally fine to run dexronIII or type f or pretty much whatever uelse specially if it has a non lock up converter. I have been told that +4 has too many friction modifyers that the A-518s from 89-93 do not need specially if it has a non lock up converter, it will make the transmission shift smoother but that comes at a cost wich is making the transmission run hotter.
Alot of guy i have talked to about this say if its an 89-93 A-518 do not use +4, and many people i talk to say type f works the best in them, as alot of people say type f works the best in 727s wich it does work well in the 727s they say it works the same in the A-518s as it does in the 727s, and another good bunch of people run dexronIII or the newer dexronVI, the new dexronVI is compatible to be used in anything calling for dexronIII just like +4 can be used in anything that called for +3, so alot of people say dexronVI is the best atf to use in the 89-93 A-518s because of its protecting ability and its heat handling ability. i have narrowed my choices down to ether type f or dexronVI so i am just trying to determine wich one would be best for me, i do have a transgo shift kit that will be installed sometime this next spring, the type f is appealing because of well it makes the A-518 shift, it also keeps it running cooler because there is hardly any slippage going on when running type f. But type f does not have as many additives in it therefore it has to be changed more regulary wich is not a big deal to me, the dexronVI however can go alot longer since it is a synthetic and it handles heat and cold temps better then the type f, but the dexronVI cost alot more the type f and it still has some friction modifyers that the A-518 does not really need therefore it will bring softer shifting compared to the dexronVI, but with a shift kit that will solve that.
So i just do not know wich fluid to use the type f or the dexronVI?