Yeah man, I don't like missing parts either, but let's be real, what do you expect them to do? Make all the parts for everything, forever? Have an assemly line right now still turning out wooden wheels for the Model T? Ford guarantees 10 years of support. Popular shit sticks around longer, and/or gets more aftermarket coverage. After that, there's always the junkyard, or if you get super attached to something, paying a machinist whatever it costs for a one-off run. 2003 was 20 years ago. Things are going to get discontinued.
Everywhere I look agrees the Mazda number I gave you to try is still in production, and even if they're all wrong, it's got multiple NOS Ebay listings. I would check it out. Report back and help the next guy who needs the same thing.
For my part, I would have jammed two different sized o-rings on there, slathered it in RTV, and driven to the junkyard yesterday to grab a bunch of those bolts for $2 a pop. If I was feeling charitable, I might limit myself to trucks marked "bad motor".