Mark, thank you for the information. I do not have a 21084 so I looked at the Doyle book. It is silent on the trailing truck style. I pulled out an older book, 1991 by Deger and sure enough it states the 21084 has the one piece drawbar/trailing truck. No variations are listed. No pictures are included of a 21084. There is a flyer website that has a picture of one but i did not trust it because some of the pictures on that site are apparently photoshopped, the 21084 picture is clearly photoshopped from the 1956 283 picture. I have several 21085's all with the diecast truck.
If you have the set number of your set but not the Tufts book I can look it up for you and tell you who sold it.
