Thanks Floridan Surfer for the writeup! You've saved me $100. If we ever meet, first round is on me!
Finally installed mine today. Got the cable off
ebay for $15. Found the other parts at a bicycle store.
The mounting nut is a 9/16" fine thread. Not all hardware stores will have it. The local auto parts store got one for me the next day. Cost me $0.23.
The local bike store had a bin full of used brake lever barrel adjusters. In the first pic by the OP, you'll notice that there are TWO lock nuts on the adjuster. Be sure to find a barrel adjuster and get a 2nd nut for it. I also grabbed a cable stop and some washers to fit it all from their used bin of cantilever brake cable bolts. Total cost, $1.00 so I gave them $2 and told the kid to keep the change.
Install the barrel adjuster on the throttle bracket under the dash first. I had to file my barrel adjuster slightly to fit the factory mounting bracket. I tightened it up with some pliers.
Take the Toro throttle and clip off or straighten the end of the inner wire so you can slip the whole inner wire out. Don't worry, the cable and housing are about 2x longer than required in our vehicles.
File the hole in the dash slightly if required. On my LX450 I had to make it a half-round hole because there were two 'flats' in the dash hole, and only one 'flat' on the cable mount.
Test fit, poke it back there, slightly to the right and then mark and clip the housing with sharp side cutters. If you accidentally crush the end, you can clean it up on your bench grinder. Having the housing *slightly* longer is better than *slightly* short.
Drop the lower dash panel (3 philips screws) and mount up the cable.
When you install the cable pinch bolt, make sure there's a tiny bit of free play so that your pedal will fully return to the 'up' position. Don't make it tight! 1/8" freeplay would be idea. At least 1/16" (1-3mm) is required, or your vehicle may never return to idle. I bolted it up, then pushed the gas pedal to the floor (engine off!) and slipped the stiff wire thru the notch.
The stiff inner wire can then be positioned so that the gas pedal hole clears the cable completely without rubbing it. I had to tweak my bracket slightly by hand to get it perfect.