I once asked that question of 'wesk' (Wes Knettle), and received the following info:
"What most folks do when no original hood number was left on the jeep is take the first 2 or 3 digits from a period correct hood number and add their jeep's serial number to the end. IE. 209XXXXX for you would work out to 20965355. The Army registration numbering system 209XXXXX numbers were what all the M38's left Willys with in 1952 because up until 1954/55 the Army was prime contractor for all tactical wheeled vehicles for all the services. The only thing the USAF did to new 1952 M38 hood numbers was tack an "F" after the USA. They maintained the vehicles using the original Army supplied registration numbers. However by the late 50's any pre 55 vehicle in the USAF had the new registration number system applied. These were initially A-XXXX type numbers but in 1959/60 they switched to contract year prefix such as 52K-XXXX."
In your case, 20913600 would seem appropriate.
Additionally, the following is a quote from an article in 'Military Vehicles', October, 2003:
"The invasion star was not normally found on vehicles
in the Pacific Theater. Additionally, it is strictly a WWII
marking. The invasion star is not appropriate for any
vehicle in the post WWII-era. Ambulances did not carry
the National Symbol in any form."
However, it's all up to you, it is yours!
