From the wording in your reply, I presume you are unaware that Martin Loftin has the correct model of the SP Overnight boxcar in his Sunshine line. It's a nice model, with the correct ACR panels and the improved ends.
You're right Garth, I'd forgotten that Martin had produced a resin kit for these cars. It's a model I can't use, and I have a hard time remembering all the different cars in the Sunshine line.