Although these offered more power and much improved reliability over the original Class 21s, they did not survive much longer, due to their small class size and the use of a non-standard high-speed diesel engine. D6108 was withdrawn in May 1969 and scrapped by McWilliams of Shettleston in 1971, while the other 19 were withdrawn between April and December 1971 and scrapped at BR's Glasgow Works in 1971–72. No Class 21 or Class 29 locomotives survive today.