replaced ATF in 97 E420, but only got out 3.5L

[ProV1]

I drained the ATF and dropped the pan to replace the AT filter & gasket. I could not locate the torque converter drain plug. Even after dropping the pan, I could only drain about 3.5L of old fluid out.

I ordered 8 qt's of OEM ATF so I'll drive for a week and just replace again w/ new stuff.

BTW, the ATF was NEVER replaced in 9 years and the stuff that came out was NASTY, black & thick. New OEM fluid was translucent red. I might just buy 4 more qt's and repeat 2 more times.