Turns out I only have three of my original Rally wheels, one has been replaced at some point and the spare is missing.  Here's what I know:

- The 3 good ones are stamped DC

- DC decodes to: 67 Corvette or 68-70 Passenger Car (That's us!)

XA 14X5 B-3 1/2 67 Chevy II with drum brakes

DA 14X5 B-3 7/8 67 Chevy II RALLY with disc brakes
DG 14X6 67 Camero & Chevelle with dics brakes
XB 14X6 B-4 3/8 67 Chevelle SS, 68-69 Chevelle with F-70 Tires, 70 Chevelle
XN 14X6 B-3 3/4 68-69 Camero & Nova with drum brakes. Different shaped outer
AE 14X6 B-4 3/8 70 Chevelle Station Wagon
XG 14X6 B-3 7/8 68-69 Camero with dics brakes, 68-70 Chevy II/ Nova with disc brakes, 69-69 El Camino without disc brakes. Wider drop center than normal
DE 14X6 B-4 3/8 71-72 Nova & Chevelle, 6 hole wheels
YW 14X6 B-4 3/8 Exactly like XB, may have come on same cars
YJ 14X7 B-4 3/8 69 Camero/ Chevy II L72- ZL1, 70 Nova
AV 14X7 70-72 Camero, 71-72 Nova, 6 hole wheel
XT 14X7 L72- ZL1 Non Rally Wheel
YA 14X7 B-4 3/8 69 Chevelle SS Wheel
AO 14X7 B-4 3/8 70 Camero &69 Chevelle SS Wheel
DB 15X5 67 Passenger Cars with disc brakes.
DF 15X6 B-4 1/16 67-68 Camero Z28
DC (BIG) 15X6 B-3 1/2 67 Corvette, No other stampings on rim
DC 15X6 B-3 1/2 68-70 Passenger car, 67 Passenger car (early models)
FI 15X6 B-3 1/2 68-70 Passenger car, 67 Passenger car (later models) Rivited instead of welded together
YS 15X6 B-3 1/2 68-70 El Camino
FW 15X7 B-4 1/4 71-up most any GM
AG 15X7 B-3 3/4 68 Corvette (will take 15x8 Beauty rings)
YH 15X7 B-4 1/4 L72- ZL1 Z28 Rally 69 narrow drop center
AD 15X7 B-4 1/4 L72- ZL1 Z28 Rally 68 wide drop center
AV 15X7 70, 71, 73 CAMARO Z28 5 spoke wheel
AZ 15X8 B-4 69-82 Corvette

- I do also have "3 11" or maybe "8 11" stamped on the other side of the valve stem

I'm told the dating works like this:

K-1-Y M <hole> D AZ

where:

K - manufacturer (Kelsey-Hayes)
1 - manufacturing plant (Romulus, MI)
Y - last digit of year
M - one or two digit month (1 thorugh 12) for month of year
D - one or two digit day (1 through 31) of month
AZ - 15X8 wheel used from 1969 through 1982

I think the K 1 is missing and my wheels are dated Nov 68, which is what a lot of the car is dated, so would make sense.

QUESTION 1:  I'm guessing then that if I want date code correct wheel replacements I need DC wheels dated Dec 68?

QUESTION 2:  Other than width and offset, is there any difference?  like will a 15x6 Wheel Vintiques wheel look the same?