Attempting to ID an odd C-64 c (?) motherboard

Hi,
I have a strange C64C (I believe) motherboard with:

PCB ASSY NO.250451
PCB No. 251915 Rev.2

...printed on it.  I don't see this board documented in the normal places
and the PCB does not come up in a search, any ideas? The VIC-II is missing.

https://www.vintagecomputer.net/commodore/64C_250451/250451_251915_pic1.jpg

Thanks

Bill Degnan