Instrument Panel change & program

I have a 97 328i
I bought the car in the US and imported it to Canada
I took out the instrument panel that read in miles (and sold it stupid me)
and I installed a German one that read in KM

I have the tool to make the milage the same on the speedo (converted to kms of course)
but now I am selling the car and want to convert it back to reading in Miles
I bought 4 different instrument panels on ebay and I have problems with all of them, 2 of them will not allow me to reset the milage
1 is faulty (garbage)
and the 4th is fine except it came out of a 318 instead of a 328 and every thing works except the rpms read to high ( I think because it is meant for a 4cyl and mine is a six.)

I think the 2 that I can not adjust the milage may be because of a small coding box that is just below and to the left of the white pin plug on the back which the other instrument panels do not have.

Can I just take the coding box out and then program the correct milage?

or is there a way I can change the one out of a 318 to read the rpms right?

I asked BMW and they said yes but they need the original instrument panel too, which I sold which started this whole mess..


Any suggestions would be very appreciated