With these issues, the postmark dates are a great way to eliminate certain color possibilities.
Hers's a photo with certified copies of all 6, in order from Michel 37 a to 37 f.

The Michel to Scott conversion is as follows:
Michel 37 / Scott 36
37 a = 36 a
37 b = 36 c
37 c = 36 d
37 d = 36 b
37 e = 36
37 f = 36 e
So the photo above would be, in order, Scott 36 a, c, d, b, no suffix, e
Here's the Michel listing showing the general dates of use for each variant.
