Yes, I use all of them, A,B,C,D.
If you use different combinations you can achieve different toe in and different widths.
For ex.:
If you use A+D for the back you have the most toe in possible which is 3.5 degrees per wheel.
If you use C+D you have 2.5 degrees of toe in which what I use.
The secret here is that you can have the same result with A+B.
Each letter corresponds for half (1/2) degree of toe in, in addition to the 2 degrees from the standard angle that the blocks have.
The difference between combination C+D vs A+B is that the first one will give you a wider car, about 189mm. the other about 187mm.
This way you can experiment with the width.
Also note that these susp.arm blocks are higher than the std ones found on the TRF 414 series.