Record Cards from 37506 whilst based at Thornaby TMD (TE).
These records date from 1985 - Last Classified Overhaul 27th March 1985
37506 (D6707 37007 37506 37604) Is currently in service
with DRS under the guise of 37604. More Information can be found here -
C37LG - 37604
More information can be found here
Wikipedia - BR Class 37 -
Class 37 Locomotive Group