Hi and welcome to tractorbynet,
I have the same tiller- it came with my S370 (along with a 42" Woods bush hog). Sorry, I don't have a manual for it. Trouble I have is that mine needs new tines and the dealer the previous owner bought the tractor from new quoted me $560 plus shipping for tines. Looks like I'll buy a new one for my kubota BX.
Another user, vppinc has posted several times that he has parts and manuals- here's his post to another user.
</font><font color="blue" class="small">( I sell the manuals and parts you need. Call toll free 800-609-5110 or email vppinc@rev.net. We have a large stock of new and used parts for these tractors. Bill Rodgers
We sell parts and manuals for Satoh/Mitsubishi tractors. 540-345-9650 )</font>
Sam