I have been reselling new Simonini "C" gearboxes for my Mohawk Aero Yamaha conversions for a couple of years and developed a good relationship with the manufacturer in Italy. Only had one issue, I objected to the prop shaft tolerances being too tight for main bearing used, asked them to reduce the size of the shaft which they did - returning the newly-machined shaft to my spec in just a couple of weeks! I was very impressed with their response and turn-around time.
Rotax refused to sell me anymore "E" gearboxes as of January 2023. (I was then the first person to report Rotax disco-ed the E box, just as I was the first person to report them disco-ing the C box. Make of it what you will.)
Then Russia invaded Ukraine and getting my AK7 and SPG gearboxes out of Belarus became next to impossible.
So I asked and was granted a USA dealership for Simonini's entire line of products last year, will update my website ASAP. Had no real interest in their engines until today. While posting on my FB group "Yamaha Aircraft Engine" about the new dealership agreement for the PSRUs I went to the Simonini site for photos to post and this led to my decision to carry and service their aircraft 2-stroke engines, WTH since Rotax bailed out of the 2-stroke aircraft business entirely may as well go whole-hog with this thing. And I've heard nothing but bad things about the Chinese MZ line. I always liked hte Italian Arrow stuff, what's not to like about Italian quality and customer/ dealer support, Simonini included?
They've been selling these "Victor-2" 100 hp motors since before 2004, I see on this thread. That makes it 20+ years. The issue reported here 20 years ago about a Ducati ignition unit failure doesn't worry me in the least.
As with everything I touch, I'm giving it my own, Mohawk name: SV-2. The SV-1 is a one-cyl variant putting out 54 HP.
The Mohawk "Sim C" gearbox shares most of the same basic dimensions with the Rotax C gearbox, including mounting bolt pattern and style which requires the top four bolts be inserted through the rear case with the front half removed.
Gearsets are $500.00, and come in the folowing ratios: 3.47:1, 3.06:1, 2.76:1, 2.54:1, 2.00:1, and 1.16:1 (diesel)