Austin morris fg lorry 1958

The original diesel engine from that period would be the BMC 3.4 litre 4 potter with the pneumatic governor, assuming that (as your truck has twin rears) it is either a FGK 40/60 or 80. Later it was uprated to 3.8 litres with a Minimec fuel pump. BMC used the payload weight in hundredweights to designate their commercial range, hence the FGK 40 was a two tonner, the FGK 60 a three tonner and so on. Those engines will be scarce now as Nuffield tractors used the same engine and tractor lads snap up any that come on the market. Personally I would stay with the 4 litre six cylinder petrol that you have, as others said it is a lovely smooth running engine and virtually trouble free. It was offered as an alternative to the diesels even in the artic units running at 22 tons GTW so has bags of power.

Pete.