My son is 10 and very excited about model trains.  We had many discussions with him before he got the Ho scale set, especially with regards to how breakable the parts were.  He has figured out now how to take care of it.  He just wanted me to order these 2 replacement parts so he could put the box car back on the track.  I am about as clueless as they come on these train set ups, so all your advice has educated me well.  Thank you!

Thank you so much for that insight!  I looked everywhere for some sort of specs on that.  I am so glad you responded.  One more question...  (since the coupler broke too)  It came with body-mounted EZ Mate Couplers.  I see that there are some magnetic ones.  I am wondering if those wouldn't be easier for my son.  He is so patient when he puts the cars together on the track, but I thought if they were easier, I might as well replace all of those as well with magnetic ones.  What's your opinion?

We bought the Pacific Flyer Train Set (item #00692) for my son for Christmas.  However, it only took a day for one of the plastic wheels and a coupler to break, all on the same box car.  I am pretty sure his plan is to get not just one new wheel, but a set of metal wheels and replace all of them.  However, I don't get what these sizes mean.  They show a 36" Flat Back Wheel Set (item #42903) and a 33" flat back wheel set (item #42904).  how do I tell which size he has?  I measured the wheel and it is 9/16" from inside to inside, 3/4" from outside of wheel to outside of other wheel, and 1" from the outside pin to the other outside pin.  Any insight would be greatly appreciated.