Cliff,
Yes, there is a later model 30 inch mechanical tiller that with various mounts fits the G100, GT235 and GT245, GX255, GX325, GX335, GX345, X465, X475, X485, X495, X575, X585 and X595 tractors.
The tines from these mechanical tillers are the same ones that bolt up to the 30 hydraulic tiller, but the mechanical unit has only eight of each left and right hand tines in the tiller width, whereas the 30 hydraulic tiller uses 10 of each. Deere part numbers on these tines are M87089 and M87088 respectively.
The newer mechanical tiller itself looks like this, but I have yet to find anything like a model number for it...
Chuck