Mth preimer sd70 ace. These engines have scale wheels that can be interchanged with hirail wheel sets so I get that part. My question about these engines is the fixed pilot with kaydees. What is the absoulte minimum curve radius these engines will negotiate when coupled to rolling stock going thru back to back curve switches? The mth rating is 042 is there rating spot on or will they fudge a little say to 036?