I have a 1979 International truck that I use to spray water on my private motocross track. It gets used a handful of times a year for 5 hours or so. I have no idea when the last time the transmission fluid was changed so I'd like to give it some fresh fluid and see if it improves shifting or at least prolongs the transmission. It call for Eaton PS-386 spec which replaced Eaton ps-164rev7. Im trying to source 8qts but cannot find anything less then a 5 gallon pail for over $200 online. Anyone know of a transmission fluid that would work in this situation that could be locally sourced in gallon containers? I have no use for extra transmission fluid as this is the only truck I own. The only one Ive found in gallon containers is Mobil Delvac transmission 50wt which meets PS-164rev7 which I can't see being a problem if I could get my hands on some.