The factory filter probably does have an anti drainback valve. Since our filters lay on their sides, this valve can be important, it prevents the filter from draining while sitting, which prevents "dry" startups and also it can prevent dirty oil from escaping the filter.
I forget which brands do have the valve so OEM is safest, but hard to find or expensive. Most of us will be in good shape with a reputable aftermarket filter with or without the anti drainback. You can often call the technical guys at the filter companies and they will tell you which filter to use and what features it has.
There are also a couple websites that cut the filters apart and tell you who makes what and what is inside. A websearch for Oil Filter study should turn it up. A lot of store brands are made by the big boys and many are excellent and much cheaper than the identical name brand filter.
I personally prefer Purolator for other cars(I haven't found a source for the LS) and they are often the manufacturer of the Motorcraft filters. Strangely, the Purolators often don't have the valve but their OEM version does.
I use a WIX brand that I get thru Rockauto on the web. Good price and delivery, and the WIX have a good reputation and at least in my eyeball comparison versus a FRAM, they are much more rugged looking in build quality and materials. I have never had problems with Frams but they do appear to be a bit lesser quality and ruggedness. There are horror stories about Fram, but then you can pick any brand get get stories. I used to use Fram on everything for many years and never had problems. I changed due to availability and the horror stories.
If you change your oil and filter regularly, you are probably safe with just about any decent brand filter.
Just my opinions,
Jim Henderson
