The Conrail GP8 and GP10 fleet originally began their lives as EMD GP7 and GP9's built for a variety of roads in the early fifties. Conrail, with hundreds of units lined up in graveyards and in dire need for reliable power decided to begin a GP rebuild program.
The railroad selected the Illinois Central Gulf RR's Paducah, KY shop to perform the work in 1976. At Paducah, the short hood high noses were chopped for better visibilty and the control stands were set up for the new short hood lead operation. The prime movers were overhauled and all former GP7's received the 567BC while the GP9's received 567C's. Air filter work was also performed, outfitting the new Geeps with Dynacell paper air filters.
Nine GP8 units were turned out during the third quarter of 1976 wearing new CR paint and road numbers 5720-5728. Sixteen GP10's were released as well sporting CR paint and numbered 7560-7575.
By 1978, Conrail desired more from the rebuild program and selected another 39 GP7's to be rebuilt. This program was not as extensive as the original consisting of only mechanical and electrical work. The dynamic brakes were removed, and the control stand remained setup for long hood forward operation. Paducah was not the only shop contracted this time around. The work was split between Chicago, Rock Island & Pacific's Silvis, IL shop, Morrison Knudsen's Boise, ID shop and ICG Paducah. The units were returned to Conrail during the third quarter of 1978 wearing 5400 series CR road numbers. The 1976 batch (5720-5728) were subsequently renumbered 5400-5408.
59 GP9's were also sent out for rebuilding in 1978 split between Paducah, Morrison Knudsen and Precision National Corporation in Mount Vernon, IL. This was the first rebuilding program PNC had undertaken and after the 6th unit, Conrail terminated the PNC contract due to quality and delivery issues. The remainder of PNC's contract was given to Paducah for completion. The same work, electrical and mechanical, was done and by early 1979 Morrison Knudsen turned out 17 units (7513-7529), PNC 6 (7530-7537) and 36 from Paducah (7545-7597). Road numbers 7532, 7536, 7538-7544, 5414-5427 were never used.
The GP8's lasted well into the 1990's and though most all were stored in the mid 80's, all but 1 were reactivated in 1987 when a batch of GP38-2's went off lease. The units were again returned to storage until 1989 when less than a dozen were reactivated again to make up for the loss of 10 MP15's that were returned to their lessor. This was the last active group until April 11, 1991 when the entire class was retired.
Low-nose GP-8 5726 lined up with PC GP38 7863 outside the Mingo Junction roundhouse in August, 1977.
The 5700 series GP-8's were renumbered into the 5400 series in 1978 to keep a solid number block and make room for further rebuilds.