51-2 and 51-3 makes reference to the last three digits of a town marshal's call. In this case, that would be Waynetown deputy's 3 and 4. For example-
54-51 is town marshal
54-51-1 Chief deputy
54-51-2 Deputy
54-51-3 Deputy
54-51-4 Deputy
It's an archaic and sort of dumb way to do it. Back in the day, when Mont Co marshals were "54-twenty something, it wasn't a problem, but now everyone get's tounge-tied with all the fives. 54-55 is a good one. So in order to not get so mush-mouth, the guys have a habit of cutting down their numbers by just using the last two (or in the case of deputy marshals, last three) digits.
In the case of New Ross, 54-50, his deputy (reserve) has to go by "54-50 R 1" because if you try saying "54-50-1" everyone would think you are Waynetown.
Boone county has the right idea with everyone but the county and Lebanon using three digit numerics, for example "401" for the Thorntown marshal, 402 for his deputy, Advance is 801 and so on, Jamestown 701 and so on, Zionsville 901 and so on...
How do I know?
I work in both counties.
*ETA*
About your "TR-1" I have no idea what that is. I've never heard it. Makes me wonder if you heard something on another group or someone ham-fisted the microphone and got distorted. Turkey Run is in Parke County.