Found it... at least on the 6 cylinders.
Under the intake, above the engine mount, on the crankcase right above the oil pan.
should look something like this
30 6M 11A
1234 A 123
11 01 - 0 123 123
Thats 3.0 liter 6 cylinder (first 3 numbers, line 1)
2nd line is engine #
3rd line is BMW part #