Personally I’m inclined to think the 3x2 launcher houses the fath missile.
compare the biggest fajr (5) rocket in this pick with the new launcher.
View attachment 760358
You can see that 4 fajr launch tubes in one row with a lot of space to spare. Hence increasing the likelihood that the new launcher belongs to the fath missile, with only 3 (larger) tubes in each row, as officially stated.
for reference, the smaller fath missile marked red in this pic:
View attachment 760359
Whats the size and ragne of that Fath missile in red?