The Stovebolt Site Forums The Shop Area Driveline 3-speed wash out

I picked up an SM318 3-speed transmission yesterday and want to clean it up both outside and inside before I install it. After I drain it, would there be any harm in filling it with either diesel or gasoline, slosh it around, and then drain it? I’d like it to be as clean as possible before I refill it with clean transmission oil. Thanks