The Dragon Pz.Kpfw.IV Ausf.H and Ausf.J kits both have the cast rear idler and the tube style rear idler. While searching for pictures I have seen both types on both Hs and Js. Which rear idler was more common on the H? On the J?

References I have show a mix and match approach to sprockets ,tube / cast idlers and rubber / steel return rollers The H was produced from April 43- July 44 ( 3774 tanks ) and the J from June 44 - March 45 ( 1758 tanks ) So there was some overlap on the assembly line .. You see Js with the new sprocket , tube idler and rubber return rollers , and Hs with old sprocket , rubber returns and cast idler .A previous thread stated that when the production line recieved new items , they were used right away , so older stock would get used up when they got to it .Seems to explain the odd combinations of vehicle parts .