Glad it worked out for you.
And NO, C41 and E6 Final Rinse solutions are not the same.
You can make a common substitute as follows:
Mix Photo Flo 200 as instructed.
To one liter of this add between 3 and 10 ml of 37% Formaldehyde solution (Formalin). The range given is what I have seen in EK formulas. I use 10 ml.
This works for C41 and E6, and works for C41 films of all ages.
See the long thread here on stabilizers for color films.