Nice jacket. I saw other units in the West wearing those parka's but never took much notice of them. We wore the standard fare during winter training in the Chicken (that's what we called Wildflecken) for those not in the know. We wore our long underwear, BDU uniform, cold weather pants and winter parka with liner. Sometimes it was cold enough to require the field jacket and liner underneath. For mounted, open cockpit movements (scout jeeps) we wore the winter cover with a scarf around our face and neck and then put our helmets on over the top, the goggled, and of course winter gloves with trigger fingers. The hardest part was keeping the cold wind off or your neck and face. Keeping warm is a matter of experience and experimentation.
Wildflecken was typically he winter training ground for the US Army in Europe and it got pretty darned cold there. There were GP Large tents at the gun range up in the hills with the stoves and those did not function well for long and required constant pumping. The cots were useless as the cold would just blow under the edge of the tent flaps and right underneath your cot. The winter sleeping bags, plus all the clothing your wore right inside the sleeping bags barely kept you warm. All I thought about and think about was the poor troops during the winters in the Korean War and WWII trying to stay warm and dry during heavy combat. We were in a secure training area with no stresses and it was tough enough. During winter training stateside we jumped into Fort Drum NY (prior to it becoming 10th Mountain Base) and did the entire winter training thing with cold weather gear, toboggans, snowshoes and ski's.
I just don't remember many of our guys in any units that had the custom parka's but then again I do vaguely remember these tour jackets. A tip to all reenactors and collectors is the M65 parka liner (the cushy green one) was GOLD! Those were lightweight, warm but breathed well enough and most experienced troops carried one in their pocket (like the poncho/liner combo). It was so easy to get on and off, could go outside or inside for immediate insulation and storage, and portable. Unlike most other cold weather gear, which was layered under the combat uniform or over the combat uniform and was difficult and time consuming to add or remove layers. Unless it was extremely cold and required long underwear for normal use, we simply didn't wear the long underwear as often because it was not easy to get on and off and much of the time you had to speed march from point to point and it retained heat and sweat too easily and that's the death nell of the infantryman. The rule of thumb for what you wear under your combat clothing, and over it, is not how you feel when you are static, but the heat buildup you are about to experience and whether or not you will overheat during that movement.
During speed marches, even in the dead of winter, many, many troops would wear regular uniforms and tshirts, maybe with gloves, because you would simply just get hot and sweaty just like in good weather. Once you stop and dry up and start to cool off, you would add layers to the outside to maintain warmth. Removing wet clothing was essential (socks and t shirts expecially). As you cool off and put on dry clothing, you *then* added layers to the outside that you can peel off. I can't remember how many times a young private in boot camp or regular duty station was cold first thing in the morning and would have on long underwear to stay warm and once we moved out would nearly have heat stroke (in the dead of winter!) because he had the long underwear on! He couldn't stop, strip down and take them off because that would require the entire unit stopping a movement for one guy. NCO's would read him the riot act and teach him to "Dress properly, not for how you feel now, but for how you're going to feel when you're humping hard and fast!"
Bottom line, if you're warm in the morning, you'll be too hot in the afternoon.