I have a 2005 trailblazer and thinking of buying a 2003 with a bad motor. The motor can be rebuilt, my question is after I rebuild that motor can I put it my 2005 ? Will it work with out having to change computer. Will the transmission swap out also?

 

It depends. What engines are you referring to? Also, at the very minimum, the ECM/PCM will likely need to be reprogrammed. I can;t answer about the transmissions.