Motor swap
Replacing motor in 2000 Mustang, 3.8L manual trans. VIN digit 4. I got a used
motor. 2002 3.8L VIN digit 4 but out of an automatic. I see my 2000 is
externally balanced the 2002 is internally balanced (have drastically diff
harmonic balancers). Is this because of year diff or manual/auto trans diff.?