First....
Second.....Congratulations on your first cub, and a good one at that. The 126 is one of the rarest cubs in the production series of IH cubs!
Third, make sure the S/G is toast before going through any added expense. Have you tried to hook up your battery charger to the post on the S/G and see if it spins? Sometimes the wires inside get all carboned up with black deposits and it makes it look bad. If it spins, then it might be useful.
Fourth, if the wires are fried inside, you can look into a total rebuild or else you can try to find a good used one from our sponsors, post an add in our Trading Post section of the forum, or look at E-bay for one. A good used one should cost around $60-$65 (including shipping), which is reasonable.
Fifth,
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Cub Cadet 123