This airplane had some major modifications done in its life. In the mid 70s KLM upgraded their Classic fleet from PW JT-9 engines to GE CF-6-50. PH-BUG was the last with JT9, BUH the first with CF-6-50. PH-BUH was modified on the production line. Then in the 80 the upperdeck was streched, to look like a -300 series. By the late 90 it was converted to full freighter, and to allow for more maindeck space, the upperdeck cabin was again shortened. By the turn of the century, KLM modified the cockpit to a glass cockpit, but still with a flight engineer. The last few years it flew for Martinair.