Is there any difference in HO scale trains between manufacturers? eg. say Bachmann vs, Tyco or Bachmann vs Athearn. is there a difference in dimensions? I have been building my 4'x8' layout with Bachmann trains and track. I'm quite impressed. Everything is working great.My reason for this post is  I recently aquired a Vintage Tyco HO train that won't run on my track very well.