All the older Cub Cadet diesel garden tractors I know of used Kubota engines. You don't see them anymore because of course Kubota has been selling their own diesel GT's. With CC now associated with Yanmar, perhaps we will soon see a new CC diesel garden tractor model.
The driveline/transaxles on all of the older CC diesels were basically the same as their gasoline powered counterparts. The Kubota diesels didn't produce a whole heck of a lot more torque than the gas engines, and usually less peak HP in the same setup, which is why the standard drivelines work fine with them. The advantage to the diesel was less fuel consumption and longer engine life- two things that would pay for themselves over the life of the tractor, and advantages evidenced in the much higher resale values the used diesels fetch.
There were no Cub Cadet diesel garden tractors built by International Harvester, the first models introduced were the 782D and 882D in 1984, under MTD ownership.
-Fordlords-