Wow, what a wealth of information.
Thank You very, very much Loco Bill, I will be ordering one of the two choices here soon. And yes I do truly appreciate it. that means that we will be able to enjoy this set for many years to come. I have used it with My children and now will be able to continue using it with my grandchildren. And hand it down to one of them someday.
Merry Christmas

First I must apologize,
This is the first time I have joint a forum (so I am not sure how this all works)
I have an old 4-6-0 Valvoline 125th anniversary G gauge train set. (Approximately 20 years old)That we only use this time of year (about 4 weeks total) for around our Christmas tree.  Lately it seems that I take more time to repair it, than I spend using it. (the chassis is in desperate need of repair) So I am reaching out for some help. I spoke with Bachmann's parts department, the man I spoke with told me that there have been customers that have swapped the old body on to an updated (newer) Chassis. And said that this forum would be a good place to start. About the only thing I can tell you is that my original chassis uses the part # G81006W old generation pilot truck (I was able to find it in Bachmann's on line catalog).Any help would be greatly appreciated, Thank you in advance