|Southern Pacific Railroad GP35R 6343 at Phoenix, Arizona on an unknown day in December 1981, Kodachrome by Chuck Zeiler. Built in February 1965 as road number 7724 ( c/n 29726 ) on EMD Order 7756, it was renumbered in the same year it was built to road number 6621. It was rebuilt to GP35R during 1979 and renumbered to 6343.
Between 1977-1979, the SP contracted with both Morrison-Knudsen and the Canadian National to rebuilt 60 of its GP35 locomotives: The 31 units rebuilt by M-K ( SP 6302-6323, 6353-6361 ) were completed between October 1978 and November 1979 and classed GP35E. The 29 units rebuilt by CN ( SP 6324-6352 ) were completed between January and December 1979 and classed GP35R.