leaf spring front mounting bracket 3/8-16 press-in knurled studs?

I actually have had good luck going to our local NAPA- they have several large trays of assorted (Dorman) press-in studs. Take one of your old studs there (bring your dial caliper along, too), look for the oldest guy in the store, and tell him you need "some of these". He'll match up the knurl and the thread and you're good to go. (They'll always be one short of however many you need, though.)
Most counter jockeys will generally try to look up a computer listing, which doesn't exist, and tell you they're not available.