RiVin Posted December 16, 2023 Share Posted December 16, 2023 My transmission's last leak is the case connector o-ring. I've looked all over for the o-ring with no luck. Can anybody give me a source or even a good part number might help. This is a 1 year only part. The case connector is a small diameter compared to the 65 & 66, thus taking a smaller o-ring. I can find them for the 65 - 66, but not for the 64. The reason they got bigger for 65 was because the switch pitch & the kickdown went through the same connector. No switch pitch in the 64. Help! Thanks Link to comment Share on other sites More sharing options...
joe_padavano Posted December 16, 2023 Share Posted December 16, 2023 Just match up the old o-ring at a hardware store or Tractor Supply. The cross section is more important than matching the exact diameter. Silicone is your best bet for chemical resistance, but viton will work. 1 Link to comment Share on other sites More sharing options...
joe_padavano Posted December 16, 2023 Share Posted December 16, 2023 I'll add that early Caddy TH400s also use this small connector and Fatsco has the correct o-rings for them. Link to comment Share on other sites More sharing options...
RiVin Posted December 24, 2023 Author Share Posted December 24, 2023 Okay folks. I just successfully resealed my leaking ST400 downshift case connector with a correct SAE size O-ring. It is a 9/16" x 3/8" x 3/32". That is 9/16 OD x 3/8 ID x 3/32 cross sectional diameter. It is readily available at your local NAPA store for 50 cents each. Very important! This is a one year only case connector O-ring for 1964. In 1965 they combined the switch pitch connector in with the downshift connector and the whole connector became much larger in diameter. Best! 2 Link to comment Share on other sites More sharing options...
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