Just FYI for people who run into the same problem.... while performing the sender unit replacement, the dealer discovered several wires that were damaged by a rodent. Apparently I had a little stowaway that built a nest near the gas tank. I'm not exactly sure what the dealer really did.... the service ticket says "drop tank found wires chewed 6 wires had to be replace and repaired wires and replace sending unit". The only parts listed include "bolt", "nut", and "seal" for a total of ~$20. Combined with labor my total bill was ~$640, but I paid $100 less with a coupon.