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T-400 tranny swap

1200 Views 5 Replies 3 Participants Last post by  ericnova72
Chazmac said:
Short tail 350 and short tail 400 are the same length, only requires slip yoke change. If you go to two piece driveshaft, use a bolt-on yoke 400 if possible.
Short tail is ~6" long
I want to put a TH400 w/4'' tail in my 64 olds cutlass (same a body as the chevelle) that already has a TH350 w/6'' tail.....

what do I have to change besides moving back the Crossmember??


sorry to wake up old thread but its very on my question
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I show a 6" tail 350 at 27-11/16" while the 400 is 28-3/8". That is 11/16" difference. Depending on how long your driveshaft is now, you may bottom the yoke unless you shorten the shaft.

You will also need a 400 yoke as the diameter and splines are different.

The 350 has a cable for the downshift. The 400 requires an electric switch on the carb or gas pedal.
redsdad said:
I show a 6" tail 350 at 27-11/16" while the 400 is 28-3/8". That is 11/16" difference. Depending on how long your driveshaft is now, you may bottom the yoke unless you shorten the shaft.

You will also need a 400 yoke as the diameter and splines are different.

The 350 has a cable for the downshift. The 400 requires an electric switch on the carb or gas pedal.
sorry , but can you explain me this? bottom the yoke :(
1964_442 said:
sorry , but can you explain me this? bottom the yoke :(
If the driveshaft is too long, the slip yoke at the trans will "bottom out" on the output shaft when the rearend is compressed(like going over a bump). This pushes the driveshaft forward, if there isn't enough travel it will try to force the output shaft into the transmission, damaging the trans.
ericnova72 said:
If the driveshaft is too long, the slip yoke at the trans will "bottom out" on the output shaft when the rearend is compressed(like going over a bump). This pushes the driveshaft forward, if there isn't enough travel it will try to force the output shaft into the transmission, damaging the trans.

now I understand hehehe and how much travel es safe enough? its a 64 A-bodied Cutlass
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