Why the 40yr rule on interchange

[Speedrcer]

Thank you all for the input and realize this is a 'Fan' forum but lots of knowledge aboard. Sneaking them by would not float as too much at stake. I've been speaking to the AAR and working with getting some more information from the FRA and will be reaching out to UP/Class I RR. The information has been conflicting from all parties. Moving via flat car is great option, although driving up the cost a bit. I was looking for options that may not have been uncovered and appreciate everyone's help.