This slip appears to be something the dealer would have added to the customer’s new car folder. The chassis number shown is a correct Vehicle Identification Number for a 1976 Buick Skylark built in the United States. The VIN is stamped on a plate which is attached to the dash in front of the driver where the windshield and dash come together. The number is visible through the windshield.
The VIN 4B69J6T108159 decodes as follows:
4 = make - Buick
B = name code - Skylark
69 = body type - 4-door sedan
J = engine - Buick 350 - 4bbl V8
6 = year - 1976
T = assembly plant - Tarrytown, NY
108159 = individual car sequence number -starts at 100001
The last 8 characters of the VIN are stamped on the block of the original engine.
L = body color (exterior paint code) - dark green metallic
63B3, 93C2 = key code - these numbers will be found on the original keys if the knockouts are still in place.
There is a Body by Fisher number plate which contains additional information. This plate is located on the front of the cowl in the engine compartment.
Does any of the data above match on your car? The VIN should be shown somewhere on the official government documents as well.