Your tiller was made in last half of 1975 in that year only HH60 engines were used. Someone add 8 hp engine later in your tiller life. Another give away date of factoring is its 2 speed after beginning in 1977 they began with 4 speeds other 2 speeds was gain by moving single drive belt to other grooves. If you join the group at yahoo groups dot com you read a lot info there its where I looked on file that had serial list for your Horse at that group there dealer phone number Bill Roger 1-800-609-5110 normal week work hours after 9 AM so hit right time zone. That model number you gave is wrong Horse only made into I, II, III, IV models in early production. Bill Give help you need if phone he old dealer and own group at yahoo. HH60 means 6hp HH80 means 8hp this you find on starter cover on Tec.

gator rider,
Thanks for the information. I thought it must be older than 1987. I will follow-up with Bill Roger and see if we can solve the pulley problem.

Take a look around on the internet. You can buy pulleys for most any shaft size and diameter. I bought some pulleys a year or so ago of various sizes. I don't remember the company I bought them from but it wasn't hard to find them.

I have a Roto-Hoe 990 tiller that I inherited from my dad that had an 8 hp Tecumseh engine that was shot. I repowered it with a 10 hp Briggs Intek engine that I got from Small Engine Warehouse. I made sure the shaft sizes were the same so the old pulley worked on the new engine but I had to make an adapter plate because the Briggs mounting bolt pattern is different than the Tecumseh. The Briggs engine works much better than the old Tecumseh.