96 V6
I was wondering if when installing a new used ECM on my car, did I have to get it programmed by the dealership...
And also are there certain different ECM's that will fit but carry more advanced programming than others

 

95/96 are the only choice AT/MT are different as well
match the numbers and you should be alright , they are already flashed and should be OK , many parameters will be learced upon initial start up