No knocking genessee, as I've only heard good things about them.. however.. you could do it yourself for less. Pretty easy to find barrrels of GM10si 3 wire alternators at junkyards.. for 25$ a pop.. that and some kustom bracketry, or even a bit of work on a universal bracket from an auto-motive chain store. Get a true 12v coil, like a napa IC14sb for 15$. If you have an ammeter, you can leave it.. it will work fine.. or if you want a volt meter.. get it.. about 9.99$ for a sunpro model.
Your oem wire harnes, if in good condition, will still work with a cut ans splice or two.
10s1 3 wire has a charge stud, #1 and #2 terminal. Jumper #2 to charge stud. Hook charge stud tot he wire that used to go to your gennies -vr -'bat' connection.. or the bat side of a cutout, if your model had a cutout only.
Hook a wire from the switched side of the ignition, thre a trailer marker lamp with a 194 bulb in it, to the #1 terminal.. that way when yuo turn on your ignition and start the tractor, you will excite the #1 terminal.. etc.
Probably do it yourself for 60$ if you got the alternator, a new coil, and a top bracket, and cobbled up a bottom bracket, and the trailer marker lamp... etc.
your call..
Soundguy