I don’t know who sells quality decals for the A4 E/F and wanted the Tomcats squadron to represent the time the A4 served in Vietnam.
VMA 211 would also work.
These will work, if you can find them
Since you will be hunting for out of production decal sheets, here is two more options for 311.
Fox One
https://www.scalemates.com/kits/fox-one-decals-48-022-marine-skyhawks-in-vietnam--333018
Cutting Edge
https://www.scalemates.com/kits/cutting-edge-modelworks-ced48147-a-4-skyhawks--202410
211
AOA and Fox One sheet plus two Superscale sheets.
These are Mike versions but you can burrow bits to make a Echo markings.
https://www.scalemates.com/kits/superscale-international-48-0969-usmc-a-4m-skyhawks--960080
https://www.scalemates.com/kits/superscale-international-48-0823-douglas-a-4m-skyhawks-usmc--959993
I will look in my decal stash as I feel I might have one of these sheets/unit markings but might not be in the right scale.
Top,
I have the this SuperScale sheet.
https://www.scalemates.com/kits/superscale-international-48-0823-douglas-a-4m-skyhawks-usmc--959993
Send me a PM with your address if interested.