We use 450's for dry controll on a litter truck, for controlling population on two different planters and have used it on an air cart to control dry fertilizer. The main difference between the liquid controller and the 660 is the units made specifically for dry have provision to input the weight of the dry material. What this means is with the dry controller once you have a calibration number all you need to do is change the density number when changing products. If you use the 450 you will need a different calibration number for each product. This is not as big of deal as it might seem because you can do it mathmatically. For example, if the density is double, the cal number is halved. So instead of changing the density you change the cal number - just have to keep a chart for each machine once you have it figured out.

Another thing is the dry controllers have more digits available to cover a wider range of application numbers. Again, this can be easily "tricked" to make the 450 computer work. For example, when we apply lime with our litter truck if we want to apply 2000 pounds, we put 20 in for the rate. This lets us use a cal number within the working range of the computer (otherwise the cal number would be down in single and/or fraction of a digit and not fine enough to get a good calibration). It works fine that way, just need to keep a "cheat sheet" in the tractor for the different machines we use them on. Have three of the 450's and the funny thing is we don't use liquid on any of them anymore. For the planter 24 for the rate is 24,000 corn population.

The other feature the 660 or other dry specific controllers usually have is additional inputs for spinner speed, low tank indicator, etc. Can't do that on the 450.

If you want to be "cheap" (like me), your 450 will work just fine controlling dry material via a hydraulic flow controll system. Been doing it for 5 years now on multiple machines. Will set up our Flexi-coil air cart this winter and a JD 7300 planter and will use the 450's for those applications. It generally costs us from $800 to $1200 to make a machine VRT which includes the hydraulic motor, Raven hydraulic flow control, shaft speed pickup, hoses, sprockets, wiring harness and odds & ends. That does not include the price of the 450 console. It also does not include any of our own shop labor or any of my "mental" labor figuring out the proper displacement motor, flow controll valve flow rate range and sprocket combinations, etc. If these things scare you better find someone that can help. It's not rocket science but a good understanding of hydraulics and ratios helps. I have a high school education and I did it so it is not something impossible.

John