the fittings on the trans are 1/4" npt. I'd go with -8an fittings and hose. You may have a problem if trying to keep the exchanger though. Those are -10 or -12an fittings and trying to match -8an hose to those sizes might be hard. You'll also need to cut the line off the front cooler from the exchanger and have a fitting pressed on. The other line off the cooler to the trans already has a -8an fitting that can be disconnected. 12ft. to 15ft. of hose should be enough