A couple of weeks ago, my 4001c64s arrived via courier. I bought it used, but if I hadn't been told it was used, I would never have known (i.e. it's in mint condition).
Here is the only dilemma I encountered:
To my knowledge, there are a few differences that distinguish a c64s from a c64.
4001c64
-black nut
-no zero fret
-glossy finish
-"hexagonal" shaped
bridge pickup surround
-"regular body shape"
4001C64S
-white nut
-zero fret
-satin finish
-rectangular
bridge pickup surround
-reshaped body (i.e. shaved "horns")
In every way listed above, the bass I received meets the c64s model specs - except 1.
The body isn't reshaped. I've been calling it "the hybrid" to this point.
It was made in mid 2003. I'm not sure weather it is a "proto-type", mistake, or
custom work requested by the purchaser. Anyhow, I love the bass, and I'm pleased
with it. I just wanted to put the info out there to get some interpretations
from folks who might know a little more about the c series bass models.
Here are a few pics.

