Since I'm partially listed in the FAQ for the front end upgrades, I thought I'd add to some of the information out there.
As many of you have found; not all "super steer" axles are the same. There's an early "low" version, and a later "high" version. The difference is limited to the spindles
I'm making an assumption, but I'd be betting that MTD saw the line of garden tractors becoming more of a single-purpose lawn mower, and with the design of a higher-vacuum deck, they updated front end to allow more clearance to remove and install the deck. The only other popular front-end attachment, the 2-stage blowers, were not on a parallel linkage like the QA series was. I happened upon this over the winter as I broke a weld on the spindle on the super-steer axle on my 169. I found, locally, a 1440 front axle. Much to my chagrin, the front end was raised about 1.5", completely throwing off the geometry of my 54" blade (sure, I could have modified the blade subframe), as well as I noticed that my QA36 blower was canted backwards off the wear edge.
So the axle came off, but before I designated it for recycling, I noticed that it was swept forward about an inch, or about 1.75" more forward than IH models, but was otherwise dimensionally identical to the "low" super steer front axle I had gleaned from a early cyclops model. Bear in mind, your drag link will need to be made porportionally longer.
Its been since blasted, and painted 2150 Red, and installed on a project. I like the forward sweep, think of the stance between a 240 utility tractor, and an 806 with a wide front, it's just more befitting of something patterned after a field tractor.
Here's the graphical description:
Comparision between the early and late super steer axles. Notice the forward sweep, as well as additional iron.
Here's the installed "before" picture with the early super steer casting.
Here's the installed "after" picture with the late super steer casting.
Enjoy!