They definitely share the same shape, but the 5V is larger in size, output, and horsepower. The 5V I believe used a 7.5HP motor, but I am not 100% sure. It DID, however, use the rotor/stator from the M-10/10V/etc. The 3V8 has a smaller rotor/stator on it.... These are definitely two very different sirens. the 7V8 is what replaced the 5V, from what I understand.gman 1 wrote:ok...I have got one final statement/question. When I searched the 5v on google images, it looked exactly like the 3v8. I don't wan't to cause trouble, I am just trying to point out the facts
You can probably still get a skirted 10V if you wanted, or a skirted 7V, and that would be about as close to the original 5V as you could get.
3V8:

5V:


Both of these pictures are mine...you can pretty easily tell how much taller the rotor is on the 5V than the smaller 3V8.