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I use the oilguard also. The Oilguard kit came with everything needed for a clean install on the 7.3L. Prior to the Oilguard I had the Amsoil dual bypass and the kit did not include all the fittings needed for the install and I had to purchase additional 90 degree fittings to make it work. Check into it before you wind up paying more.
Another OG user here. Very happy with it. Running 13K miles between bypass and full flow element changes... heck... 13K miles between oil changes for that matter... getting excellent UOA reports.
There is a design detail between the two which can sometimes be problematic for Amsoil system purchasers. Amsoil's filter head allows for a 10% bypass flow whereas OG's design is for a 5% bypass flow. Depending on where you mount your bypass elements with the Amsoil equipment, too long of a hose run (greater than 4 feet, if I remember correctly) can cause a drop in oil system pressure in the engine, which was verified by Amsoil's Tech Support when I was researching which system to purchase.
I have the Amsoil bypass and like wht buffalo said you will need to purchase some 90 deg fittings. You will also have to make a bracket to hold the filter assembly. If you go to Amsoils web site there is a link to customers pics of how they did theirs. I like mine, very well engineered and straight forward to install. Roy