I've been looking at the C-200 lately and here's what I've gleaned:
The C-200 came out in 1973. The X version came out in 1980. The L version in 1984 and the V version in 1987.
The cosmetics basically stayed the same, but each version changed the internals.
The X version is DC coupled and added a head amp for MC carts.
The L version changed the layout of the internal cards and power supply to be similar to the 280 and added a balanced output.
The V version changed the internal cards again, added 2 balanced inputs, but dropped the 2nd phono input and the front phono input.
The specs for the 80s versions are very similar, but the measurements they put in the brochures definitely look different.