What would be some of the more noticable differences between a 2001-2003 Schwing 31EZ boom pump and a 2006-2009 model year of the same machine? I am wondering mostly about things such as pump cells, vector controls, digital/analog boom controls etc... Are there any major design upgrades on the newer (06-09) models?

For that model, the  biggest difference is in the electronic controls, meaning Vector and radio remote (twistknobs); the design of the boom is still the same, possibly minor upgrades, pumpkit hasnt changed either; why change a winning team?

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you got that right gboom