I wonder if anyone knows what the id is on the soft rubber hose portion of the transmission line that goes from the trans to the cooler?

I am wondering becuase I want to install a Magnefine filter on it.

Thanks,
Ryan

Replace all lines with 1/2 inch oil proof hose for much more flow (there' is a reason Diesels use 1/2 inch
you will cut your backpressure about 15 lbs for each line and another 15 lbs if you use a 1/2 inch in and out cooler and bypass the radiator
If you are in a cold weather state let me know

I hadn't planned on changing them completely, I was going to splice in a filter and needed to know what the inner diameter of the hose is so I could put barbs into it, in order to mount the filter. The sizes I am wondering are 3/8, 5/16, and 1/2". I'm ruling out half inch due to above post so y'all think its 3/8 or 5/16? Thanks

That is interesting about the bigger lines reducing pressure and I do live in a cold climate state.

most likely 3/8
cold climate state use a thermostat or route through radiator and cooler.
WE put gauges before and after cooler and at input and output of trans.
The 3/8 lines are much better than the old 5/16 but not near as efficient as 1/2
What tranny do you have?
late tranny has a filter
I use the filter before the coolers to protect the expensive coolers from converter failure not just to protect the trans after the cooler

wymrider is correct, it is 3/8"