I have a question on ecm's my truck is a 1999 classic it has the 350 vortec I know its not an ls but I replaced the motor in it and it came with a cam so I been running the cam and the ecm is tuned by nelson and im wanting to go back stock. stock cam and ecm. my question is can u use any vortec 350 ecm's. I found a 98 ecm and was wondering if it would work with out any tuning done to the ecm? im not sure on this and need some help?