PLEASE NOTE: THIS WILL NOT WORK FOR ‘ZILLAS MOUNTED ON THE FACTORY BRACELET.
The factory bracelet has a unique mounting bracket, and there are no adapters commercially available. There were some prototype adapters made, but they proved to be too expensive to manufacture, so production was never started on them. If you happen to see a set for sale…buy them…they’re ‘rare’ 
.
First, the one-piece adapters to use a Zulu type strap. These adapters will only allow you to thread a one-piece strap thru them. You cannot mount a two-piece strap.
Examples (pics from Walter):
Second, you can get an adapter that uses springbars. You’ll notice the lugs are drilled thru to make strap changes easier. Also, notice in the first photo that the adapters are actually on upside down (there is a bigger bevel on the lug that should be facing upwards). Compare the lugs in the 1st and 2nd photos to see the bevel in the 2nd photo. Also, in the 2nd photo you’ll notice that you can fit a bracelet to the adapters as well. If you think about it, both this type, and the 3rd type can use one-piece Zulu type straps as well…you get the all the options with these two adapter types.
Examples (again, pics from Walter):
The last type is an adapter like the springbar adapter, but using screws instead of springbars. This is a much more robust setup, and involves more machining, so I’m sure this is the most expensive option.
Examples (pics from Walter):
So, you want to know how to do it, right?
Okay, first, start with an unmodified Zilla:
Next, set out your adapters (I installed the strap also, to see how it looked). Also, notice you cannot see a bevel from the back when looking at the adapter on the right (it’s flipped under, so you’re looking at the back of the adapter). The adapter on the left had poor lighting…so a comparison isn’t easy…sorry 
):
Turn the watch face down, and you’ll see 4 slotted screws (pic from PMWF):
Carefully use a screwdriver to remove the screws. There was no thread lock holding mine in, so it shouldn’t be diffulcult. BE CAREFUL, if you slip, it’s quite possible to damage the caseback, or yourself.
When the screws are out, it will look like this:
The ring on the back should come right off, and you’ll see this (notice, the rubber straps have their own integrated adapters):
At this point, the rubber straps with their own integrated adapters should slide out. You might have to rock them side-to-side a little to get them to pop out. Here’s what they look like when removed (notice the retaining ring in the background behind the rubber, and a couple of the screws off to the left):
Take a look at the adapters again. Notice, you can see the larger bevel, as this is the top of the adapter (note how the leather is installed). It’s purely cosmetic, and will not affect function. If you install it upside down…you’ll probably never notice. If you closely examine the lug tip to the plastic tray I’m using, you’ll see the underside doesn’t have much of a bevel at all.
Okay, so slide the adapters down where the rubber straps were, and it will look like this. Just to beat a dead horse, here you should be able to make out the lack of a bevel on the lug tip on the back side of the adapters:
Insert and carefully screw down the retaining-ring screws. Make sure not to cross-thread the screws. I rotate them counter-clockwise until they ‘click’ down, letting me know they’ve seated into the start of the threads. Then I thread in clockwise to prevent such a disaster. Once installed, it will look like this from the back:
And here’s a wrist shot (and now you can see the larger bevel at the tip of the lug…facing outwards 
):
It may be hard to tell in the lighting, but there is a gap between the adapter and the bezel area. This is normal. If you were to look at the rubber, you’d see how thick it is at the mounting point. It’s thick to create a slope from the watch head to the rubber. Once it’s installed on a strap and you start wearing it, you’ll forget about the gap.
Any 24mm two-piece strap should work (rubber, leather, silicone, and bracelets)
Topher1556
