I've looked though both the BBB and Arsenal and I can't find a laser designator that I can mount on a drone without adding in a weapon. So do any exist, and if not, whats a reasonable amount of capacity for one to take up?

I mean a Laser Rangefinder is only 1 capacity.

Why not just add the Laser Designator modification to a drone? 1 or 2 capacity should be fine.

I equip pretty much everything with a laser link, but I imagine they're fairly different tech, right?

If I'm understanding the question right, you want a laser designator without having the designator be an accessory to a vehicle mounted weapon. Although you could easily justify using the handheld designator by itself in a weapon mount (many handheld laser designators are pistol shaped, so this would be not much different than mounting a pistol itself), there are also options for drones that have no more weapon mounts left, or aren't big enough to have a weapon mount in the first place, so that might not be a viable option either.

However, this is one of the things that the "Special Equipment" vehicle mod is for. As for capacity, I'd say it's negligible, since you can always use the miniaturized version of the laser designator that can be mounted inside cybereyes.

What page is the laser designator modification on? I mean I know where the one that can go on guns is but I don't see one for drones.

I may just have to house rule it but I was trying to make a standard solider type that followed the RAW and I was going to give him a Fly-Spy with a Laser Designator.

Only if you think using the Special Equipment mod, which was designed to be a catch-all for many situations not covered other places in the rules, to be "houseruling" it. Seriously, I don't see "Special Equipment (Cybereye-sized Laser Designator)" to be any less valid than "Special Equipment (Cute Looks)" and the latter is RAW standard equipment on one of the drones from Arsenal.

What page is the special equipment mod on?

Special Machinery/Storage, p.144-145 Arsenal

(Apparently, they only call it "special equipment" in descriptions of the stock vehicles/drones.)

Thanks, I'm just going with a Laser Designator/Range Finder as capacity 1