One of my horses is insulin resistant, so he is not permitted to have anything with molasses or soy.
The only two vit/min supplements, to my knowledge, that are completely free of both are:
1) Equipride, which is what I feed. EquiPride? And EquiLix? 1-800-327-9222
2) LinPro Foxden Equine Nutrition & Therapy - LinPro
As far as "feed" is concerned, I will stand corrected, but I think you're only options are molasses-free beet pulp or equine rice bran. I say equine rice bran because it has to be calcium fortified and stabilized so it doesn't turn rancid.
I feed Equi-Jewel. Equi-Jewel main
If you have a local Co-op store, Co-op (ours in Middle Tennessee does) make and bag their own feeds, including equine rice bran.
Southern States may have their own rice bran under the "Legends" name, but I'm not sure. Here's a well-written article from their equine nutritionist. Something New in Rice Bran - Southern States
If Producer Feeds sells in your area, be sure the G/A tag has been sewn on the bag. I can get Producer Feeds rice bran but the store hands me the guaranteed analysis tag. I am sorry but that is illegal and how do I know I am getting pelleted rice bran as opposed to something else
Hope this helps