Jim
You've got a good memory...yes, I think you were there when Dave was looking at them.
I had told him that I only had a pair of the smaller NOS 318 ones, technically 318 used no resonator,( just head pipe to over axle pipe )
He said to bring them and after examining them at the show, said he could open them.
Whether he actually used those or found the correct larger 2 1/4 before the car was totally finished I don't know.
Irreguardless, the NOS I showed is 2 1/4 as were the 3 that I showed removed from original 340 cars, as would VCODE Bobs be, so one hole or two holes, shouldn't have dictated size of pipe used.
Again Davids hanger has no holes and appears to be correct 2 1/4.
Part number on his tag would say 3404932, same as on my box 3404932, same part number number for both sides, application 340,383-4, 440, 440-6, 426.
Supply and demand I think.