The fact that the D/Darts were regular production line automobiles may account for the LO LP discrepancy. There are no trick body panels or trim differences to differentiate a D/Dart from a 273-4v Dart GT. I'm suspicious of the white car VIN plate. Uneven spacing and line not straight.
LO 23 D 6 2 653932
LO - Dart Superstock
23 - 2 dr hardtop
D - 273 CID V-8 (all 2v & 4v had this designation in 1966)
6 - 1966 model year
2 - Hamtramck Assembly Plant
The last six numbers are the assembly plant sequence number. Each plant started with 100001 regardless of the car line. EXCEPT HAMTRAMCK built Valiant and Dart models which begin at 500001. (emphasis mine)
(source Chrysler Corporation Production Production Option Code Book 1966 - 1968, Fourth Printing, Jan. 1996. page 1. Galen Govier ed.)
Not all Darts and Valiants were assembled at Hamtramck. The sequence number would put this D/Dart car pretty deep into the production run. That would put this car well into 1966 limiting a team's ability to tweak on it before putting it on the track.
Here's the PR release that I have on the D/Dart program. Wish there had been a date on it. I have no idea how many retro-fit kits were sold.
Dodge Offers "D" Stock Dart
DETROIT -- A new 275-h.p. Dodge Dart GT that meets D Stock specifications of the NHRA, AHRA and NASCAR is now in production. The "D/Dart" has a shipping weight of 2,946 pounds.
The "D/Dart" features a modified 273-cubic inch engine with a special four-barrel Holley carburetor. Other features include:
A special Camcraft camshaft (284 degrees with .495 intake and .505 exhaust), Racer Brown valve springs, a modified, full-breathing intake manifold, a low-restriction air cleaner, and a Weber clutch. Other standard items are: a heavy-duty 4.86:1 Sure-Grip 8-3/4 inch rear axle, free-flow exhaust headers by Doug of California, a four-speed manual transmission, heavy-duty suspension, and 6.95x14 B.S.W. tires.
The "D/Darts" are regular production line automobiles.
Additionally certain, basic service parts will be available through the Chrysler Parts Division, so that owners of earlier Darts may convert from the 235-h.p. to the new 275-h.p. version of the 273 V-8 engine.
The "D/Dart" has been certified by the sanctioning agencies in the D Stock class. It is expected that this car, properly prepared, will be a top contender.
A high idle speed minimizes roughness, a high numerical axle ratio is used for top acceleration, the distributor is modified for quick advance, and the ignition system is designed for optimum engine output. Due to the expected use of these vehicles, no warranty coverage applies.
Those who are interested in more specific technical details on this car may contact staff engineer Dick Maxwell, Product Planning, Chrysler Corporation, 341 Massachusetts Ave., Detroit 31, Michigan. Phone 313-883-4500, ext. 3947.
In case your local Dodge dealer does not have a full list of the part numbers for these specific components you may wish to contact performance parts specialist Ray Ryder, Chrysler Parts Division, 22631 Lawrence Avenue, Centerline, Michigan. Phone 313-539-3000, ext. 7763
