Can some one tell me the pros and cons about a N's R5,6,7's and the R40,50,60, and 70's. We currently have a 6600 with about 4,000 engine hours and we are looking at Gleaners. I have no experiance with them and i don't know what one to get and wich one not to get. I also don't know what year of a machine to get. Thanks to any that can help.