There is no plastic in the ZD, there is on the Exmark but its the radiator sheild, Both units look strongly built. I think with the increase price of the ZD there are options, or I should say things more pleasing to the operator which I would consider OK. But that is why I narrowed it to these 2 machines, and I think highly of the ZD's Motor, will last longer and be better on fuel consumption. As far as lasting as long as a tractor, I don't know-Maybe, but the tractor is more versital etc, mowing, rototilling, brushogging. By looking at them the ZD's look like there built to last. One ? I would like to know if anybody has actually used or saw the results of a ZD's cut, Ive seen Exmarks and there's are good. Also I forgot to mention above the fuel tank on the Ex is plastic, did'nt check the Zd's but think that is industry standard