These Mustang heater box clips are the replacements I used to hold my 1966 Mustang heater box together after rebuilding it. The clips squeeze the case halves together around the heater core and keep the gaskets sealed.
I used them on my 1966 Mustang, and CJ Pony Parts lists them as fitting the heater box on 1965–1973 Mustangs.
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Mustang Heater Box Clips at a Glance
- Replacement case clips for 1965-1966 Mustang heater boxes
- Hold the case halves together around the heater core
- Help keep the new gaskets compressed and sealed
Why I Replaced Mine
Several of my original clips were bent, and some were broken to the point that they wouldn’t go back on. With a fresh gasket kit, you want the case held together tightly.
Fair warning: compressing the case halves with the core inside is a fight. Go easy, because the housing is a fragile fiberglass-type material. I felt mine make a small fracture noise when I pushed too hard.
What Comes in the Pack
Each pack comes with 4 Mustang heater box clips. The heater box uses 8 clips in total, so one pack isn’t a full set, and it isn’t meant to be. It’s for replacing the clips that have broken, bent open, or gone missing over the years.
That’s exactly what I found on mine. A few clips were bent open or broken, and a couple were missing altogether. One pack covered what I needed, and I reused the originals that were still in good shape. If more than four of yours are bad, plan on ordering two packs.
Signs Your Clips Need Replacing
- The clip is bent open and no longer grips the case edge
- It’s cracked or snapped
- It’s missing, leaving a gap where the case halves can separate
- The case halves sit loose or uneven once the box is assembled
Fitment
I installed these on my 1966 Mustang. CJ Pony Parts lists the same clips as fitting the heater box on 1965–1973 Mustangs, so they should work on later cars too. Double-check the listing for your year before ordering.
Who These Clips Are For
- Anyone with bent, broken or missing heater box clips
- Owners rebuilding the heater box with a new gasket kit
How I Installed Them
- Assemble the heater box with the core and new gaskets in place.
- Gently compress the case halves together.
- Snap the clips on around the edges of the case.
- Add a little black adhesive at the seams if any spots won’t stay tight.
Mustang Heater Box Clips FAQ
How many clips does a Mustang heater box use?
Eight. One pack has four.
Do I need to replace all eight?
No. Replace the ones that are broken, bent, or missing, and reuse the good originals.
Do these fit a 1967–1973 Mustang?
CJ Pony Parts lists them for 1965–1973. I’ve only installed them on my ’66.
Can I reuse my original clips?
Yes, if they still grip tight and aren’t cracked or bent open.
What happens if a clip is missing?
The case halves can loosen, and the gaskets won’t stay compressed around the heater core. That lets air leak out of the box instead of flowing through the core and out the vents.
When is the best time to replace them?
During a heater box rebuild. With the box already out of the car and apart, it’s easy to check every clip. Getting to them later means pulling the heater box out again.
See It in Action
I used these clips in my 1965-1966 Mustang Heater Box Rebuild. The post and video cover the full rebuild.