The vent section must be removable.
See here in the MOM pic, the slots are Vertical on this pack
But you can see that the circular round portion is a separate piece than the pack and the detailing is different than the AOSW pack.
and it's the same pack that is in the "Star Wars the Exhibition"
Which is the same style as this PP1 pack, but a totally different pack
as you can see in this AOSW pic, the vent portion has been replaced with a non-matching section. It appears to be glued over the original hole
and also this pic from CIV
The AOSW, CIV, and ROTJ SE Promo pics use the same pack
Which is also The Heilman Pics Jetpack. you mentioned above.
The weathering scratches are exactly the same.. Not just really close, but EXACTLY THE SAME.
here's a comparison of the Heilman (left) and the AOSW,CIV, ROTJ SE Promo (right)
Regarding the symbols on the packs, You can see them faintly in the comparison shot above.
I added the fullsize pic below (just keep clicking it)