This thread drove me to consult the 'bible' on Olivers-the John Goodall book published in 2004. The Mk4 wasn't available till 1967-not 1964, and Oliver production (as opposed to repair, rebuild etc) wound down in the early 1990s.(ca 1992) Tom Ridley's Oliver production didn't get underway till around 2010 or thereabouts-so there is a nearly 20 year period when Mk4s were not in production. Even allowing for the Ridley production that's less than 30 years cumulative......

If we want to be facetious-people are still building the Sparey 0.8cc diesel-which dates back to 1946/47....

I agree that the PAWs whilst in continuous production since 1957, have gone through various model changes (and size changes-there are two different sizes of PAW 19s...!) over that period......I'm beginning to think perhaps that my comment on the Dart may well prove to be closer to the mark-if we're going to use the yardstick of internal parts interchangeability......and the Merlin-which appeared in 1954, lasted till 1984...

ChrisM
'ffkiwi'