From the 2007 thread about this, here is the approx address if the mini mart/gas station on the west side of southbound CA-99: 5650 E Lathrop Road, Manteca, CA.
We could meet that at 11:00 AM.
How does that sound?
google map of this area
I cannot find the exact address of the mini mart, but it's just north of the address pointed to on the map. If you turn on the "satellite" mode of the map, you'll see the building just south of the on/off ramps for southbound CA-99.