I was wondering if the ST3505 used a combo valve. However, 3505 an odd number (likely a consolidation of a couple filter apps) and based on an earlier bitog thread seems it replaces the more standard 3506 in the closed out ST line. That is confirmed using Fram X-ref. If so, then this for older GM with block bypass so no filter bypass required.
That being the case, I think it most likely a silicone adbv got used on the one filter. If one goes to the Wix site and X-refs the ST3505, the 51042 with a silicone adbv shows. Base end looks just like the one ST3505. In addition to the markdown, seems you got a bonus with that one.