Its F L/Kp 48 not 40. as we know similar stampings are commonly seen on Luft First models but whos to say when that stamping was done? I dont like the 8 being a double stamped o our German friends were more regimented than that.IMO someone defaced a really nice Buchel 2nd Luft in an attempt to hump it up ask yourselves why we havent seen others similarly stamped over the years.Is there any provenance info on where it was bought etc available?