This one lacks the HH sleeve reinforcements and has horizontal seam tapes on the upper arms. I wonder whether it is a "one-off" or has had the sleeve reinforcements removed. The Talon zip appears to be a replacement as it ends a couple of inches from the waistband. Interesting jacket.
http://cgi.ebay.co.uk/WW2-USAAF-B-3-SHE ... 0235449886
http://cgi.ebay.co.uk/WW2-USAAF-B-3-SHE ... 0235449886