TM 11-264.pdf  Manual for Radio Set AN/GRC-26.  December 1950.
TM 11-5820-202-10.pdf  Operator's Manual, Radio Sets, AN/GRC-26A, B, and C.  January 1959.
TM 11-5820-256-10.pdf  Operator's Manual, Radio Sets, AN/GRC-26D.  June 1969.
TM 11-5820-256-20.pdf  Organizational Maintenance Manual, Radio Set AN/GRC-26D.  5 January 1962. 
TM 11-5820-256-24P.pdf  Repair Parts and Special Tools Lists for Radio Set AN/GRC-26D.  July 1977.

These files are made available with the compliments of August Johnson, KG7BZ.