the Dragon kit of the Panzer 4 ausf J is the late version
the Tamiya kit of the Panzer 4 Ausf J is the early version
the tank in the german musium is a Ausf J early for the reasons ive already stated it looks od becouse its got no side skirts on
there are Pazer 4 Js like the model in Battle of the Bulge then and now ISBN 0 900913 40 1
and also in the Encyclopedia of german tanks of world war two ISBN 1 - 85409 - 214 - 6
this is a Quote from this book
"The main change introduced with the Ausf J was the elimination of the electric traverse and its associated auxiliary engine. The armour thickness of the turret roof was increased and a Nahverteidigungswaffe added as a smoke projector and for close defence .
Minor improvments introduced during the production run included the deletion of pistol ports and vision ports from the turret rear and side doors , wire mesh skirting on the hull sides , 3 instead of 4 return rollers , vertical exaust mufflers , and the hull sides extended beyond the front hull plate and drilled to provide holes for towingshackles"
as for a musium not making mistakes http://rongeorge.com/modules/Gallery/ww2armorref/panther_f_turret_1 this was a Panther Ausf F turret that was at Bovington tank musiun in the scrap area (the only one left in the world)
Deakon nice model are you going to place it on a diferent base?