The Dennis Dart had evolved in terms of accessibility from the original high-floor variant to one with a low floor section at the front, often with split steps at the front with the one nearer the wheel being lower. The SLF Dart was the next step, giving low-floor entry as well as a low floor through most of the saloon. It went on be a very popular chassis indeed. Rhondda Buses bought four, of two different types. All in the first month or two received prominent markings advertising their low floor and easy entry. :
- The three for the Parfitt's fleet in Rhymney Bridge were 56-58 (P56-58 XBO), Dennis Dart SLF SFD322 with Marshall Capital B43F bodies. They carried Caerphilly Busways fleet names.
- The vehicle for the Rhondda fleet was 54 (P54 XBO), a Dennis Dart SLF SFD322 with Wright Crusader B43F body, the only Wright Crusader in the fleet. It entered service a month later than the other three and was the last new bus delivered to Rhondda.
Unsurprisingly, all these vehicles survived to the Stagecoach takeover in 1997, after which they were renumbered 554, 556-558, later becoming 33554, 33556-33558 in the national numbering system. In later years they were based at Brynmawr and were scrapped in 2011.
