Peel peaches, dice, and mix with sugar. Add to crock pot and cook on high for 1-2 hours, reduce heat to low and continue to cook 6-8 hours; stir occasionally. Remove lid and use and immersion blender to puree until smooth. Leave lid off crock pot and continue to cook to desired consistency, stirring occasionally. Prepare canner, jars and lids. Ladle hot peach butter into prepared jars, leaving 1/4 inch headspace. Remove air bubbles and adjust headspace, if necessary, by adding more peach butter. Wipe rim and center lid on jar. Screw band down until resistance is met, then increase to fingertip-tight. Place jars in canner, ensuring they are completely covered with water. Bring to a boil and process pint jars for 10 minutes. Remove canner lid. Wait 5 minutes, then remove jars, cool and store.