5.38 To 4.27 Swap. 64' Cj5 With F134 / 4 Speed

Is there any way to know how which teeth/spline count I have without having to pull the t-case cover and count em? I just recently used permatex on there to stop a leak lol. It would be awesome to not have to redo that so soon.
Is it based on year/make/model?

 

Open it back up. There is no telling what has been done over the past 60 years. You will then benefit from getting the right parts the first time. Unusual, right?

 

It likely has a 29 tooth gear, but as said there is no telling what has been done over the years, and it might have a 26 tooth gear, or even a 27 tooth gear.

If you are planning to buy an overdrive you would have to open it back up anyway, and you don't want to buy something this expensive by guessing which one you need, and find out you guessed wrong after purchase.

 

As stated, the sure way is to pop the cover. That said, you can measure the intermediate shaft diameter and probably guess within 5%. Extremely unlikely to be a 27 tooth with a 3/4" shaft. 26 tooth are most often found with the 1 1/8" shaft and also unlikely in this case. The 29's with the 1 1/4" intermediate would be most likely. The spline count is almost assuredly six as the 10 spline was only used with the T14 transmission. But again, not in anyway worth the hassle ordering the wrong OD. Pull the cover----

 

The 27 tooth gear is rarely found. I think it was a military application, but not sure about that. Still, removing a few bolts, scraping off some gasket sealer, and verifying what is in there is a lot cheaper than spending money for an OD that won't fit.

 

27 tooth was WW2 MB/GPW and super early CJ-2A as stocks were used up.

 

Also when you pull the cover to check the tooth count, it's a good time to verify you have a socket to remove the nut holding on that gear. I don't remember offhand what size mine was but I had to go buy a socket to fit. It was larger than my impact set went up to.