Charlie

There's a few differences for sure. BUT, I know the truck tires were an option on the 600, but I've never seen a 600 w/implement tires. We had a 440 w/implement tires once & it did not ride as nice on the road as the truck tires. Implement tires are too spongy, I think. They are also more expensive. You didn't ask me, but I'd probably not buy a 600 w/implement tires. They're not the same rims either.

The 600 had a lesser pull-thru reach as others have said. It's OK, but the design has been improved w/the 640-644 series. I'd examine the back 1/2 of the reach & make sure the holes aren't enlarged that bolt the reach 1/2s together. That seemed to be a problem. But-it's fixable.

The 640 came wired for an external chute light. Not a big deal. The 640 will hold a few more bus...slightly different design. The empty weight is higher on a 640...if that means anything to you on the road. We've never broken a spindle on either 600, 640, or 644 wagons (or their Unverferth brothers). The 640 uses 10 bolt hubs, the 600 has 8 bolt. The 640 had a slightly different door design that kept it straighter when opening.

You're talking to the guy that started Brent using the side windows. They had them on the front of their grain carts, but not their wagons. We bought grain cart windows & put them in wagons. Wrote to Brent & they went with the idea. No patents involved, we were just glad to help. You must be looking at an early 600. Our 600 is a 1991 & I believe it came w/windows.

Either wagon is good used material (but I still feel the same about the tires). The 600 should obviously be less $$....all other factors considered. New wagons went up appreciably the past couple of yrs.

Good luck.