According to the website, the MK II chasis will accept SKS - D, M
Copied from the above link:
The SABERTOOTH MK-II is compatible with original fixed internal magazine, duckbill style mags, and with SKS-D and M models. The removable dustcover block enables easy cleaning and service, and seamlessly blends with the chassis when installed. The SABERTOOTH MK-II is recessed at the rear of the receiver to allow the optional addition of a top rail over the receiver.