LED upgrade with bulb numbers interior/exterior


1st Gear Poster
Sep 24, 2023
Eastern Oklahoma
Vehicle Details
1994 Ford Thunderbird LX 4.6L V8
Country flag
Did this a while back and thought I would share.

Changing interior bulbs to LED (and some exterior).

NOTE 1: leds can be polarized meaning the have a positive and negative. If the bulb does not illuminate, simple flip or rotate it 180 degrees and plug it back in. If you are replacing dim-able bulbs, make sure the led bulbs you buy are also dim-able.

These round bulbs only light up on one side, so point them correctly when installing.
-Round, fuse type dome/map light bulbs in my 1994 - #578 X 3
-Round, fuse type Vanity mirror light bulbs in visor - #6614 X 4

-Rear dome/side panel light bulbs are #98 which cross reference to #1156 X 2

-Bought a bulk pack of #194 for door, kick panel, 3rd brake light, license plate, under hood, and trunk bulb. These bulbs all have the same base, so no need to buy other sizes.
#194 will also fit the glove box, under hood bulb.

I decided I needed more light in the trunk and under hood than the 300lm of the 194 bulbs, so I bought some #921 led bulbs that put out 500lm. Much better for my old eyesight. I have very dark tint on the car so I replaced the 3rd brake light bulbs with the 921s also.

NOTE 2: Since the 194 and 921 led bulbs have the same base, they are interchangeable. The difference is in the length of the bulb (0.96" for the 194 - 1.26" for the 921). Brightness would most likely weigh in the most in your decision on which to use.

1. Headlights were the most drastic change. I absolutely love the change of color from yellow to daylight white. Of course brightness was the best upgrade.
2. Reverse/Back-up bulbs are the next best investment for me since I have such dark tint. I was having to roll the windows down to see out the mirrors. These things are like 2 small flashlights pointing out the back.
3. The dome light is almost too bright, but I can actually read with the map lights now. The rear dome/side panel lights in the rear even look good through the brown semi-burnt lenses.
4. Door, kick panel, and license plate bulbs are perfect at 194 bulbs. For me, the 921 bulbs were just too bright for these positions.

So far, I love all the changes to led. I haven't once thought "I'm changing that bulb back." Car just seems newer.

I'm not in a hurry to change the rest of the Exterior lights.

Hope this helps.

To help with searches:
Interior bulb numbers
Change interior bulbs to LED
LED Headlight bulb
Reverse light LED bulb
Conversion to LED bulbs
Thanks for the inspiration and guidelines: I never would have done this without your post. I thought I'd add my experience with my 1997 and the interior lights to this, as there were some slight differences in places.

Centre; one. The big thing I found here is making sure you get the right mm size of bulb, in addition to the general 578 light type. The first one I got was 44mm and so wouldn't fit right: I eventually blew out the fuse trying to make it both fit and stay on (it still generally fit, but would only flicker at best, due to bad contacting). It turns out you need 41mm.

Side manual; two. For these I did need the larger 44mm: for the 1997 at least the centre light and side light mounts of the dome aren't the same size.

One. With the trunk I think the more the merrier in terms of brightness, due to the bad positioning of the bulb housing. So I first used this 650-lumen variant:
It's nice, but if I could find even stronger I'd take it. So I then moved to their 900-lumen version:

For the footwell bulbs I used 194s, as per above.

I decided to have a bit of fun, however, and made the main dome light and the two footwell lights green, to match my car's Willow Green interior and Alpine Green paint (as well as the interior instrument lighting and the car stereo I added). For the two side dome lights (the ones with manual activation switches), while I upgraded them to LEDs, I left them white in case I really need to light things up and be a bit more practical. However, the three green lights together are powerful enough that it's not been an issue: I can see fine inside at night when I open the doors, and when you hit the unlock switch on the remote it lights up beautifully.

If you're curious, the green 194 footwells I used were these:

And the centre dome single was simply the green variant of the white 41mm I linked above.

All these bulbs were available in Canada as well. Here's some shots, with the manual white dome side lights off.


Last edited:
650 lumens? At some point, we just need to ignore those specs because they're clearly lying. That's the same brightness as a 60W incandescent.

The biggest problem with the trunk light is its position on the lid. Even when I was running just one bulb back there, I ran the wiring into the trunk under the package tray where it's more useful instead of having a bulb on the lid. Now I have both.

Yeah, that's a lot nicer. I'll have to look at doing that.
Thanks for adding the additional info. I'm sure it will help others.

Similar threads