I really don't know aboout your truck, i never heard of Motor Oil in an Automatic. I have a Hydramatic in my 59 Cad, and it is supposed to have type "a" fluid. I use,and have been using Dexron for 12 years w/o a problem..
ATF is amazing stuff nowadays. It comes as the factory fill in Standard transmissions in lots of cars. I think you could use Dexron. Just my 2 cents.
