Thanks Medal driver . The rear gunner did indeed have a seat and a tubular looking scope that allowed full vision and operation of the turret. The gunner sat under the glass in a chair and the scope looked submarine like with full turning radius however part of the window did open but I can not tell the proper location.
I have looked at hundreds of pics and also looked for the classic Squadrin Signial ‘Walk Around” . The only one online is being sold by the original author at a whopping $149.00 for a book that typically sells for $19.00 lol