To Flush, Or Not To Flush

The 70 CJ I am rescuing sat outside for nearly 30 years, uncovered. The PO did have the shifter covered with plastic to keep water out and the rest of the drive train was covered by the body. To be safe, I checked the tranny fluid and it was watery. My question is whether to just drain and refill, or flush with something first? Flush how and with what? Planning to do same process with all components.

 

Drain, fill, drain, fill a few times. Idk about about any solvents, hate to break down any oil if you didn't flush it out properly

 

If I get water in my transmission, I drain the milky water/oil out and refill with diesel. Drive it around the parking lot a few times then drain. You would not believe the crud that comes out.

 

Had the exact same thing.
Put new oil in with atf 50/50.
Drove around on farm, in each gear, in summer weather, bout 30 min, then drained.
Did this twice.
Then put straight gear oil in and drove couple months , then changed again.

 

This is a problem I know, the reason I don't know, but the result was, for me : rusted parts in the gearbox, it cost me some money.

 

I would probably pull the cover/floorboards and remove the shift tower and look inside.
Any time there is evidence of water, it's usually not good.
At least you would know the general condition and could go from there.

 

I was just lucky maybe, 1st drain had at least 6oz milky something with oil?
Atf mix worked for me?
Have u drove it yet?

 

Haven't driven it yet. Towed it home. The shifter does move smoothly through all gears.