Yup, the slide player was the late Hoyt (I'm pretty sure) but the theme music was definitely Al Caiola. He was an LA studio guy who released a number of albums under the titles "The Hundred Guitars Play....Western themes, Romantic Music, Mariachi, Songs For Lovers...etc." Well you get the picture.
In the sixties Epiphone came out with the "Al Caiola" model guitar, which was a glorified ES 335 with a Dodge transmission (or something) on the face plate.
As MBO might say: JOE MAPHIS RULES!