Here is the body number from my same 9-27-28 Phaeton. The "TC" means it was built at the Twin Cities Frod Plant and the 476 means it was the 476th Phaeton body built at that plant for that model year. That's a low body number for a 9-27-28 gas tank date, but there wasn't much demand for an open car in Minnesota.
You can see the number is actually partially covered by the seat riser, and the seat riser is bent rearward a little, which exposes the number better.