Pvt. Jack R. Daniels, 18, basic trainee in Fort Ord's 3rd Brigade, died of pneumonia early yesterday morning at the Fort Ord Army Hospital. He had been admitted to the hospital early Saturday morning and died 24 hours later. He is survived by his father, Jack E. Daniels of Framingham, Mass., and his mother, Mrs. Hope Tortorich of Salt Lake City, Utah. Prior to entering the service two months ago, Mr. Daniels was living with his grandmother, Mrs. Vera Platts of Bountiful, Utah. Funeral arrangements are pending and will be handled by Healey Morturary in Salinas.