Guys its been awhile since I got into the 44 tonners. I see there is about 3 versions of them. Whats the same on them?, whats compatable and what was the time line on these?. I gather the latest may even have even newer features. Looked at parts page but it showed only one unit. Mechanical improvements any?, I did see brass gear set up different on two units. Not sure though on truck gears and set up.Info on this would be helpfull.Even on Ebay when you purchase you don't know what unit you are getting as you only see picture of unit with shell.Regards . . I have single motor units with 5 gears showing on bottom and trucks newer versions with smooth bottoms, are the gears same in side?Steve