Riding With the King (Reprise 9 47612-2; 61:20) is both a dream project for rock star Eric Clapton and a love letter to his biggest inspiration. On the inside panel of this brilliant blues-drenched CD there’s a picture of a much younger, much thinner B.B. and a Cream-era, hippie-styled Clapton sitting atop matching Fender amplifiers and picking their respective axes. That vintage snapshot suggests just how long this collaboration has been in the making. On the cover, a current-day Clapton is pictured behind the wheel of a black Cadillac convertible (with fins), chauffeuring a regal B.B. who sits in the backseat with Lucille. More than 30 years have passed between photos but the bond these two guitar heroes share is still there. While there are some nods to concert rock on Riding With the King, like on Doyle Bramhall II’s “Marry You” and the “Layla”-esque “I Wanna Be,” the great majority of selections here is downhome, gritty and inspired, with the common ground being the almighty blue note. B.B. squeezes warm-toned blue notes and roars with unparalleled, sanctified intensity on signature pieces like “Ten Long Years,” “Three O’Clock Blues” and “When My Heart Beats Like a Hammer,” and he wails triumphantly on the raucous upbeat shuffle “Days Of Old.” Clapton, steeped in the blues tradition since his mid-’60s tenure with John Mayall’s Bluesbreakers, more than holds his own on B.B.’s home turf. There are two mellow acoustic offerings in Big Bill Broonzy’s “Key to the Highway” and B.B.’s “Worried Life Blues,” which sounds like Clapton and King sitting on the back porch strummin’ and moanin’ the blues-and it’s interesting to hear B.B. transpose his signature Lucille licks onto acoustic steel-string guitar. For something completely different, there’s a bluesy reading of the Johnny Mercer/Harold Arlen ballad “Come Rain or Come Shine,” with string arrangements and orchestrations by Arif Mardin. Joe Sample provides real deal, gospel-flavored piano accompaniment throughout Riding With the King, sounding particularly churchy on “When My Heart Beats Like a Hammer,” while Steve Gadd lays down a wide, loose backbeat that organically fuels this meeting of two giants.