Hello everyone! My 1999 mustang v6 that I have had since I have been in high school finally blew a head gasket. The 3.8 engine has well over 230,000 miles on it so I’m thinking it’s time for an engine overhaul. I’m confident I can do an engine rebuild but as I was looking for rebuild kits I stumbled upon the old discussion of building 4.2 from the 3.8. I have read almost every post out there and there are two topics I don’t fully understand still about this build. The first is the ecu. Do I...

3.8 to a 4.2 Build