On Chavez Siding Rd. on the east side of the Santa Cruz River.. Possible de Anza new trail, connecting both Tubac to Elephant Head..
Have walked to both trailheads from here along the R/R tracks. South to Tubac and north to E.H. The cache is to the west of the trails along the tracks because of the ROW restriction.
If you walk north, along the R/R tracks to Amado-Montosa road, here's some info:
Trailmarker guides(wavepoints), not cache locations:
#1 N 31 38.885 W 111 02.729
#2 N 31 39.308 W 111 02.862
#3 N 31 39.973 W 111 02.820
#4 N 31 40.461 W 111 03.043
#6 N 31 41.986 W 111 03.183
#7 N 31 42.250 W 111 02.996