Ken - I looked into both those units, but I don't think either of them were using those names in 1916 when he joined.
Ady - I posted on the website you suggested, they think it might actually be the 13th CMR, but I don't see his name on their nominal roll.
I've requested his service records, I think I'll have to wait until I see them to find out for sure.
Thank you both for your help,
Greg