For anyone with the JD 47" snowblower that's interested, I found an actuator that gives you 99% of the spout travel available and uses the factory mounting holes for the manual spout control kit. The actuator I used has built-in limits that give 4" of travel which works out perfectly for using the factory holes.
Here's the materials I got from
http://www.dcactuators.com/
Product ID: 302.130_6104T
Description: 4" Linear Actuator (Speed 1/2" per Sec.)"IP65 Rated" - Price: $114.00
Product ID: 302.660_8639T
Description: Mounting Bracket For (T) & (TP) Series Actuators - Price: $7.00
Product ID: 306.580_242
Description: Momentary Off DPDT Rocker Switch - Price: $5.25
I used the clevis bracket at the bottom and a bolt with a spacer and nylon washers at the top. The clevis bracket gives you just a little bit of offset. This gave me 100% of the up travel and about 99% of the down travel. The spout is slightly below horizontal when it stops so this works for me. I started with clevis brackets on both ends but this gave me too much travel or not quite enough depending on which way the bracket was oriented. Also - the clevis bracket needed to have a little material cut off the end to allow the actuator to work with the bracket flat like this - no big deal. I put nylon washers behind the moving parts to let things move freely and not scratch the paint all up. And I used a two-wire flat disconnect at the front of the tractor for removal of the snowblower in the spring.
....thought this list of materials might same someone some time.
BTW, the JD kit is $114 for the manual cable spout control, but each specific tractor application needs 2-3 brackets and some miscellaneous hardware. In my case, the other stuff added up to another $100 so this is much less expensive.