My "new" '74 Duster- or why I need a project like a hole in the head

Jarlaxle said
The threads are long on advice...short on data. I need to replace my lights (lousy Amazon LED), and am reluctant to drop $700+ without hard data.

Reasonable question as there are lots of self styled experts, and many of them active on internet forums...
For some, like Daniel Stern, that's his real name and a search engine will bring up enough that you may feel comfortable that he is a professional in the vehicle lighting field, and working from data and measurements when possible.

I'll give you some links that may help you see where he is coming from, and what sort of information he uses, along with how it corroborates with some other knowledgeable sources on the internet (and there very few I put in that catagory).

Mattax said
A good, solid, web resource for automotive lighting:
Candlepower Forums: Automotive, Motorcycle.
Browse or use the search function as appropriate.
This is an additional resource to what Dan posts here, not an instead of.
For example, Trucklite LED turns up this
7 inch LED conversions

(Dan Stern has an example of how many more lumens produced at different voltages here Daniel Stern Lighting Consultancy and Supply)

Mattax said
Ask for the photometry isographs. That would give a better idea of the effectiveness than the photos.
'Virgil' on candlepower forum or 'slantsixdan' here might be willing to help review and interpret them.
Dan has a little introduction here, and some examples.
The How and Why of Beam Isoplots

Posts here on an example of spotting misleading markings Modern Headlights Stern's website has some lists explaining the meaning of many of the lamp markings.

I realize this is all a sidetrack from a build thread, but thought it was appropriate to answer the man's question.