Mono/Stereo Carts?

No,
if you mean 'micro grove' vinyl monos and no old shell-lack monos which use a very much thicker stylus geometry. (Like a fire-poker compared to a sawing needle :-)
You'd then be using your poor stereo cart to scrape along the bottom of these old mono discs.
The other issue is that your stereo cart will translate vertical movement on your lateral only mono-vinyl into grove noise.
If they are clean it might be no issue, otherwise you need to press the 'mono' button (if you have one) or do some other 'tricks' with your TT cables to sum the signal to mono.
Some (most?) even prefer listening to (clean) monos with the normal stero signal, including myself.
Good luck,
Axel

its ok..no

Thanks for the input.I recently found several Frank Sinatra,Julie London era LPs that are in excellent condition.All are mono but clean up very nicely with my Nitty Gritty some are even sealed.I do have a mono switch.I have had some bad luck before and am on my 3rd cart that is why I asked.

You can play all that stuff with your stereo cart. Your bad luck lies elsewhere.