the first Vermeer bales like the A had a wide belt on the bottom to start the bale and keep it turning. I have not seen any of these balers around for a long time the wide belt is costly to replace. The 605 C came out in the early 1970's it had rollers on the bottom for the bale to form and turn the bale. The feed rollers were spring loaded so they could pull in the hay. These balers worked good in alfalfa in straight grass sometimes you had problems. If the bale did not want to start turning when first starting the bale you might have to loosen the chains that pull the belts tight . With the looser belts you could get more hay in the chamber to start the bale. A bigger bunch of hay is easier turn to get the bale started. You also had a soft core bale meaning the bale's center was not pack real tight. You still had trouble with the hay coming out between the belts instead of turning. Or if the bale did not want to start the belts would slip on the top rollers get hot and start smoking or the hay get jamedin the feed roolers and have to clean it out by hand and have to dump the hay to try and start another bale.
I still have a 605 C and use it on grass and alfalfa you just have to have patience with the baler but you can get it baled.
The baler is actually just belts, bearings and roller chain
The 605 C do not bring much money on auction it all depends on the condition of the belts. Some balers bring scrape metal price.
I think they did have a D baler but the next popular baler was the F.
It had what they called an open throat meaning no intake feed rollers instead of rollers on the bottom for the bale to turn it had a shaft with triangle like blades to turn the bale.
The hay had no where to go but in the baler and roll. Making it so much easier to start a bale
The F is an older baler probably early 80's or late 70's only bring 1000-1500 depends on condition.
Then Vermeer came out with the G, H, I, J, K and M all differant modifications to make baling easier. There were 605's and 504's the later making smaller bales.
There were differant models that I do not know about differant area's of the country had differant balers.
The H baler is getting some age on it so some of them may not bring to much on auction