Speedometer Cable O Ring

I'm getting a persistent oil drip from my speedometer cable at the D18. I've tightened it as much as I dare but it's still seeping fluid. I have seen a mention somewhere of putting an o ring at that joint. Is this a common practice? Does anyone have a part number suggestion for that application?
Thanks,
Ken

 

I did it. I can't remember what I used. Maybe a washer from a nozzle on garden hose? I got CRS so I dont know.

 

Same here. Bought a variety pack from auto zone and found the one that matched. I coated mine with a very thin coating of gasket sealer. No leaked so far (from that spot at least)

 

Like the others, I dug around in a variety pack to find one that fits.

 

X whatever. I have a “kit” with probably 30-40 different sizes. Inexpensive and very handy. Especially when you don’t know exactly what size you need.

 

Here's the housing I just bought. It has a flat washer style gasket.

 

Thanks for the replies. I'll pick up an o ring assortment and see what fits

 

Later gear housings had a seal like the one Scott posted but the seal was much wider. The issue is if you have an earlier gear with the spiral groove. The idea of the groove was to pull the lube back in the transfer case but the seal cannot seal against the groove. The later gears had a smooth shaft. My understanding is at one time, maybe through the dealer, a retrofit kit was available. This has been discussed here before. An o-ring inside the threaded cable retainer that seals against the end of the housing works fairly well.