The new eco from Trutrak will, I think, do what you want. They aren't out in force yet but theres a very brief write up at http://kitplanes2.com/blog/2015/12/test ... autopilot/.RonFranck wrote:New question about auto-pilots. I'm, at this time considering using steam gauges in my Panther as I have a full panel from a donor C-150 sitting on the shelf. What auto-pilot set-up might I consider? I'm looking for heading and altitude hold should I find myself on a long, VFR cross-country flight. Thanks.
That said, several of the older Trutrak models (that aren't currently listed on their website) will also do what you need. The digitrak and altrak would give you what you're after. You could likely find them for sale relatively cheap over on vansairforce or maybe avionicslist.
Final note, most (all?) of the standalone autopilots won't have a magnetometer and can't slave to a DG so they won't be tracking heading. They will be tracking a GPS ground track. If you hook them up to an appropriate EFIS then you can track a true heading.