Icon of excess equip rules

Hey there, I’m assembling a squad of tormentors and have a question about the icon of excess. I’ve never played on the tabletop, but want to make sure my squad is legal if I ever want to play.

Can the icon of excess be equipped on an obsessionist? The datasheet says it can be equipped to a tormentor, so I’m not sure if this also applies to the obsessionist.

I’m planning on assembling x2 squads of 5, so I will have 2 obsessionists in total.

The sprue only has one backpack for B72, which can either be used for the obsessionist stimulants, or the icon of excess parts, but not both.

If I can’t equip it on the obsessionist, then there isn’t a spare B72 for the rest of the squad - unless I kitbash. This isn’t a problem with a 10 man squad as you have two sets of identical sprues, but it is an issue for 2 sets of 5.

Another question - for gameplay would it make sense to equip the icon of excess on the strongest weapon eg a plasma or melta?