It was actually standard in the ETO. All P-47 had a insignia added under the left wing usually 55 or 60 inch diameter, the right wing sometimes still had the 40 inch insignia though many were increased to the 55 or 60 inch.
Though there is always an exception to the rule and a few P-47's have been seen without any insignia under the left wing in the ETO.
What colour scheme are you doing?