Yup- Deep Gap. Old Doc did a great job with Merle on Deep River Blues, also Jimmie Rodgers' Blue Yodel No. 33- California Blues. Believe Merle used a Sears & Roebuck 13/16" deep well socket for his slide on that last piece. I have about 4 vintage tapes of Doc and Merle in concert- including the one they did at Carnegie Hall in NYC-


"The field is the touchstone of the man"..