I cut open a Tough Guard about 2-3 years ago and it had the cardboard end caps. Now that was back then - things could have changed by now.
Just yesterday I cut open a Fram Extended Guard (Fram XG16) that I'd run for 5K miles. It was a very well made filter : metal endcaps, silicone ADBV, coil-spring loaded bypass, and thick synthetic media. This is Fram's best filter, and my first experience with one. It's badly overpriced compared to other filters with similar features. But I got it on sale and I knew ahead of time that it was a good filter. If it wasn't for the high price, I wouldn't hesitate to use these (XG series) all the time. Normally, I use the WIX/NAPA 1068, which has very good filtration specs and all the other features of the Fram XG (other than synthetic media), but at half the price.
Phil