Factory Cab Lights

[Uncle G]

Louisiana must have gotten a lot of trucks that were California equipped . The dealership mechanic said he installed lots of cab lights back in the 80's. Almost all of the C20's running around home had the lights. 

[Jason S]

More likely that the U01 marker lamp option wasn't selected when the dealer placed their order with Chevrolet. 

Similarly, rear bumpers were an option and a lot of these model trucks went to the dealers without a factory installed rear bumper. The dealer would install the rear bumper, usually an aftermarket variety, when the truck arrived.

Factory tachometers were also optional, but appears those weren't regularly selected either.

[Engineer]

When I ordered my ‘02 2500HD it specified that the cab lights weren’t available on California trucks. Not that it matters since I ordered my ‘02 with the cab lights from a dealer in IL.

What is California’s reason for this?

[Irish_Alley]

Cal. Veh. Code §24011.
Whenever a federal motor vehicle safety standard is established under federal law (49 U.S.C. Sec. 30101 et seq.), no dealer shall sell or offer for sale a vehicle to which the standard is applicable, and no person shall sell or offer for sale for use upon a vehicle an item of equipment to which the standard is applicable, unless:

(a)The vehicle or equipment conforms to the applicable federal standard.

(b)The vehicle or equipment bears thereon a certification by the manufacturer or distributor that it complies with the applicable federal standards. The certification may be in the form of a symbol prescribed in the federal standards or, if there is no federal symbol, by a symbol acceptable to the department.

which means if theres a federal regulation on something it cant be offered for a vehicle that doesnt meet those standards. the clearance lights by federal guidelines are required on all vehicles/trailers over 80". that being said "clearance lights" are on the sides of trucks and trailers. if over 80" you have to have clearance lights by federal standards (duallys). the 3 center cab lights are called "identification light" thats to identify that the vehicle is over 80" and the outer lights are stilled called "clearance lights". the purpose of the 3 "identification lights" is more of a universal signal to say "im over 80"" there is no other piratical use for them, theyre not to see if youre going to clear a bridge but only as a sign for other drivers and the outer lights are to see the width of the vehicle.

all that being said my 91 crew cab SRW with Cali emissions has the roof lights but NY state (where my truck is from) also uses Cali emissions.

"Code of Federal Regulations"
https://www.gpo.gov/fdsys/pkg/CFR-1999-title49-vol5/xml/CFR-1999-title49-vol5-sec571-108.xml

[ehjorten]

Here is the latest and greatest of FMVSS 108: https://www.ecfr.gov/cgi-bin/text-idx?SID=8b3d691516eeeb525c0e57c76550af23&mc=true&node=pt49.6.571&rgn=div5#se49.6.571_1108

It is slightly easier to read, but still is a pretty poorly formated specification.

The interesting thing to note is that in Section 5 it states: References to SAE publications. Each required lamp, reflective device, and item of associated equipment must be designed to conform to the requirements of applicable SAE publications as referenced and subreferenced in this standard. The words “it is recommended that,” “recommendations,” or “should be” appearing in any SAE publication referenced or subreferenced in this standard must be read as setting forth mandatory requirements.

Clearance and identification lamps are covered under section 7.5.

The latest writing of the FMVSS specification removes references to SAE J standards, however, SAE J2042 that deals with Clearance, Sidemarker, and Identification Lamps for Use on Motor Vehicles 2032 mm or More in Overall Width states the following in the Scope:

This SAE Standard provides test procedures, requirements, and guidelines for clearance, sidemarker, and identification lamps intended for use on vehicles 2032 mm or more in overall width. A clearance lamp, sidemarker lamp, or an identification lamp conforming to the requirements of this document may be used on vehicles less than 2032 mm in overall width.

One clarification is that it is for vehicles that at 80" (2032) or more in width.