In the mid-1970s, Southern Pacific borrowed a batch of Burlington Northern SD40-2s and RCC cars (converted F7Bs) in order to test the Locotrol systems installed in them. The tests must have been successful, as the SP purchased units with Locotrol in them. Sitting on the ready tracks at the SP's West Colton Yard in Bloomington, California, on March 5th, 1976, is BN SD40-2 6800 (the former BN 6340) and an BN RCC 110 (ex-BN F7B 629, nee-GN 309B). On adjacent tracks are SP C628 3133 (ex-SP 7122, nee-SP 4863) and SD35 6910 (ex-SP 4826). None of these locomotives has their original numbers!
