A real good thread, but that doesn't look like the Sears GT18/6 I have. Is this the one with a shaft from engine to a right angle drive, then a pulley from there to the tranny??
Also, it would be REAL helpful if you could post some of the basic dimensions of the electric power steering unit--would help the rest of us contemplating the same thing know what kind of space is needed.
I tried to take some pics for you of the steering mechanism inside the chassis but they came out pretty poor as the chassis and tower are all back together and the engine is in. My model # is 917.255910, the frame is 13" wide. Essentially what I did to make it fit was cut off the long shaft on the Saturn box until there was about 1 1/2" left. The other shaft on the the other side I left as is. Both sides were splined (metric) but I didn't mess with trying to find adapters, would've been too long. I just took a 3" piece of 5/8" DOM, bored half of it out with a 47/64 bit, and the other half with one over 3/4. I slipped these over the Saturn box shaft and welded it up. I basically kept the stock steering shaft (from the wheel to the stock steering gear) the same length, I just cut the difference out to make the Saturn box fit if that makes sense. I had to reuse the stock steering shaft because there's a taper for the steering wheel as well as reusing the gear on the end of it. I'd be happy to answer any questions and will try to take more pics if I can find some good angles. I'm still not out of the woods yet, still haven't wired it up and tested it yet so it's not a done deal. I can say though that I don't think this would work on a hydrostatic as the shaft going from the engine to the hydrostat would really limit the amount of room you have.