I can confirm that Wabash has some new T-Mo 3G coverage. There is still a coverage gap between Wabash and Peru on US24. Going north on SR15 once the coverage in Wabash fades out there is a gap until just south of Silver Lake. I don't know what the coverage on SR13 north out of Wabash looks like, it may be similar. I figured out that the 3G network uses a separate LAC than the GSM network, that's why I was confused by it earlier.
Hopefully existing coverage along US30 will get a 3G bump.
Phone history: NEC Talktime 800, Nokia 5120, Motorola V66, Siemens M46, Siemens SL55, Siemens SX1, Siemens SL65, Siemens SL75, Nokia N95, Nokia N81, Nokia N8