IH Farmall 656 gas/ IH 240 Utility/ 2, Super C Farmalls/ 2, Farmall A's/ Farmall BN/McCormick-Deering OS-6/McCormick-Deering O-4/ '36 Farmall F-12/ 480 Case hoe. '65 Ford 2000 3 cyl., 4 spd. w/3 spd Aux. Trans
I'm going around the horn here to answer your request, and hope it leads you to what you are looking for. I did a quick search for that Toyosha 3cyl. engine, and found this thread from another forum.
I then did a Google search for Sandy Lake Implement, and found their site. They have a page dedicated, showing their staff, and found "Brenda". Brenda Knauss is their parts associate. You might try giving them a call, and see if she can assit you in finding that gasket. Some of these gals are pretty sharp on their parts. An IH dealer I used to deal with had a gal that was VERY good with parts. She knew where to look, or cross reference to find what you needed. Could be worth a shot..!!