re:
.. The only thing not stock are the two LED cube lights, each drawing 26w.
well that's only another 4-5 amps
BUT... there's ALSO the heated seat pad....maybe 10 amps ???
With LED's one can't go by the claimed package values. I've measured 8 different sets of LED lights and the actual current draw is significantly less than what's typically published. Measured data puts it inn the neighborhood of 35% to 50% less. I believe most claim using the max rating of the individual LEDs, but they don't drive them anywhere near max rating.
I don't know why Kubota hasn't gone full LED to aid with their marginally sized alternators.
To the OP (wholegoods price list is older and should verify before ordering):
DEFOGGER KITS
L8340 Defogger Kit, Rear Window Requires High Amp Alternator Kit 28 lbs $281.00
L8381 Defogger Kit, Corner Windows Requires High Amp Alternator Kit 18 lbs $307.00
ALTERNATOR KITS
L5533 High Amp Alternator Kit for L3560 $463.00
L5534 High Amp Alternator Kit for L4060 / L4760 / L5460 / L6060 $463.00 $463.00
I added the corner window kit to my L4740 and it was a easy swap. (Already had the rear defogger).