'68 Road Runner hardtop production?

When was the start of production for '68 Road Runner hardtop models? Is there a serial number that they started with?

Figures I've seen for '68 HTs are 15,156 w/383, and 169 w/Hemi.
383s - 6686 4-speed, 8480 Auto
Hemi - 108 4-speed, 61 Auto
Mid-model intro, around Dec/Jan if I recall correctly, but haven't found a specific date, though I'm sure there's a factory memo to dealerships with that info.

The serial number would vary by plant.

So that would be plant (Lynch Road, St. Louis, LA) then Scheduled Production Date (SPD) and then VIN but that wouldn't mean the lowest VIN was an earlier build as it would fall back to the SPD. Is this correct?

I thought the 1968 Road Runner hardtop (RM23) was introduced at the same time as the Super Bee coupe (WM21)
A = Lynch Rd. Detroit, MI ** G = St. Louis, MO ** E = Los Angeles, CA

early VINS from my database:
RM23H8A22xxxx * mid-January
RM23H8G20xxxx * early-March
RM23H8E13xxxx * late-January

WM21H8A21xxxx * mid-January
WM21H8G20xxxx * early-March
WM21H8E14xxxx * mid-March

something was going on (plant improvements?) at St. Louis "G" in Jan/Feb 1968 - it appears they only produced ~8000 cars in 2 months St. Louis also added Chargers during the first week of March 1968

I have a 68 road runner hardtop. It was built in LA, and the SPD is 1/31.

Why did LA lag on Superbee production?

it's just what I have (there may be earlier cars?) - but production planning on a new vehicle may have felt that Detroit had the capacity to handle it? Road Runner was already a proven "SELLER"!

Thanks. My Road Runner had a scheduled production date of 2/6/68, Lynch Road built.

Only about 7800 '68 Bees :

4,783: 383 Engine / Automatic Transmission

2,933: 383 Engine / Manual 4spd Transmission

94: 426 Engine / Automatic Transmission

31: 426 Engine / Manual 4spd Transmission

Not sure if it was just less popular than RR or just got a later start, maybe both?

Both.

Dodge never would have produced the Super Bee if it didn't witness the success of the RR.