421 was an early 1970s Dennis D series, which came with either a rather troublesome Jaguar petrol or (if you were lucky) a Perkins six cylinder diesel.
423 was a slightly newer HCB-Angus bodied Ford D series, which had the option of a Ford turbo six cylinder diesel or a more powerful Perkins V8 - which was also used by Dennis, Dodge, ERF and Shelvoke in other fire appliances at the time.
423 was a slightly newer HCB-Angus bodied Ford D series, which had the option of a Ford turbo six cylinder diesel or a more powerful Perkins V8 - which was also used by Dennis, Dodge, ERF and Shelvoke in other fire appliances at the time.
Added by Rob Johnson on 09 April 2018.