El Gigante ranch was located west of Harlingen Texas at the far end of Dilworth across the arroyo colorado. there is a wodden bridge that crosses the arroyo now.

Info later provide by Sebastian Villarreal on El Gigante is as follow:
You mentioned "El Gigante", the name comes from a huge bone that people used to go across the Arroyo, it was down stream from La Feria Vieja...I did a lot of treasure hunting there so had other people 100 years before me. I never found anything. The Location is where Adams Garden road crosses the Arroyo on the right before you cross.

The "El Gigante" bone as I remember was of a large diameter 8-10 inch or so...it was without a doubt in my mind a dinosaur bone...it was located not too far down stream from La Feria Vieja site.