Polaroid's folding automatic Colorpack cameras have a PC socket/jack for external flashes, but you can't just attach any old electronic flash and automatically get correct exposure.
When these cameras were first made there were no cheap, small or portable electronic flashes. Everyone used bulbs. The timing for triggering a flashbulb is called M-SYNC. While the timing for triggering an electronic flash is called X-SYNC.
The difference between M sync and X sync is the timing in relation to when the shutter is fully open. Because flashbulbs take a few milliseconds to get to full brightness, but electronic does not, M triggers fire before X triggers do, in order to allow time for the bulb to reach maximum brightness. What this means is that your electronic flash will fire and even expose your shot, sure, but it will do so just a tiny bit too early that it can cause exposure issues with your photos. Not always, but sometimes.
Working with electronic flash
The camera's auto-exposure works with continuous light sources (ambient light) or flashbulbs, but not the super fast electronic flash. Your flash must have its own automatic exposure control, and be able to be set to f/8 at ISO 100. Otherwise you may end up tweaking your camera/flash alot to get proper exposures. Which isn't impossible, just more work.
Mounting the flash can also be a problem as these cameras don't have a flash shoe. You'll need a bracket that holds the flash, a coldshoe mounted to the body, or some other way to get the flash where you want it. Taking the bottom from the #268 flash for automatic packfilms and somehow mounting your flash to it could work.
Using electronic flash
All Automatic Packfilm cameras have a standard PC connector. Your flash will obviously need the appropriate PC cable, or a shoe adapter with a PC plug could work with any flash. You should be able to find these items in any photo store or online.
Once you've got a suitable flash on or near the camera:
A problem you may run into is the shutter not closing after the flash. This occurs because the photocell doesn't "see" enough light, remember electronic flashes are too fast for these cameras. Once you take the photo and the flash fires, let go of the shutter button to end the photo and you should be fine. Or you can keep holding down the shutter button and "drag the shutter" as one is able to do with many dSLR cameras today which have "slow flash sync" or whatever they might call it. This exposes the flash but also lets in more ambient light, giving a more creative and less flat look to your flash photos.
How to modify the shutter for X-sync
If you are up to the small challenge, there is a small modification you can make to your camera which will properly trigger your electronic flashes when the lens is fully open.
Open up your shutter's housing by removing 3-4 screws from the backside. The front half of the housing should now come off, the back is attached to the bellows and struts, leave it be.
Now once inside the shutter's circuitry will either be on the front or back half of the housing. Either way you should see two small copper contacts which, when you set the shutter lever, come apart.
If you play with the shutter, you can see how they work in relation to the mechanics of taking a photo. These copper contacts are the controllers for the flash timing.
Depending on which model you have, find the largest aperture opening and set the camera to it. Which is typically 75/Color/Dull Day or whatever your model possesses.
Using a finger to hold the shutter darkslide away from the lens it will move one of the copper contacts away from the other and allow you to now see thru the lens.
Look for the point where the lens opening and the leading edge of the darkslide are in line with one another, this is when the shutter is fully open. Now bend the copper contact so that it touches the other exactly at this point when the lens is fully open.
Your camera is now modified for x-sync timing!