A compilation of railfanning from December 2020 and early July 2021 to answer the question...where are NS's former GP59s?
Two examples of these locomotives, a class only rostered by Norfolk Southern and intended for high-speed intermodal and Road-Railer service, found themselves purchased by Carload Express, an Oakland, Pittsburgh-based holding company for shortlines in eastern Ohio, western PA and the Delmarva Peninsula. Though the GP59s have occasionally seen service on the Southwestern Pennsylvania Railroad in Westmoreland and Fayette Counties, the GP59s (and the ex-NS SD60Ms) have mostly remained on the Allegheny Valley Railroad in Allegheny and Washington counties.
The GP59s spent most of their initial assignments sandwiched between two SD40-3s working the Island Avenue transfer job; occasionally, however, they could be found working the mostly-daily AVR-3 local run to Washington, PA. In December, CLXX 4552 (former NS 4617) led two GP40-3s on an unusually long AVR-3 heading north through Finleyville, PA.
I spent several months away from Pittsburgh, but returned earlier this summer. AVR-3 has been running at night to accommodate almost-daily trackwork on the former B&O "Pike" and I was fortunate to catch one of the ballast extras conducting work at Bruceton (the Wheeling & Lake Erie interchange). Here, CLXX 4551 is pulled off the head end of the southbound train to allow the crew to drop half of the cars on the interchange.
CLXX 4551 used to wear the latest "Horsehead" paint while on NS (as opposed to 4552's older-style Thoroughbred paint with OLS logos), which is wht it has the white 'unibrow.'
An ancient Lake Erie, Franklin & Clarion County hopper brings up the rear of the ballast string coasted onto the interchange track.
The 4551 guides the train as RJ Corman contractors drop ballast on the main at Bruceton.