clock generator and 6501

Dear Sirs,

In my application I need three 8-bit ports.
My boss bought a 6501 USB device and I communicated with it and it works properly.
Now it occurs that I need one clk output to establish 3 clk frequencies: 50Hz, 47Hz and 52Hz.

The problem is that on 6501 there is no clk output.

Is there any Ni Device that covers 3 ports and 1 clk output, or other device eith  clk output only?

Is it possible to echange 6501( I have other packed) for other device in Ni distributor?

Best,

Chris