Topic: 66 mustang convertible 4 speed transmission

[69cobrajetrugae2]

This Mustang has a C code 289 with a T-10 4 speed built on June 4, 1966 San Jose.  Is this the correct transmission or was it born with a top loader?  Thank you in advance.

[midlife]

66's could come with either the T10 or the toploader.  Midlife came with the T10, but I switched to the correct toploader.

[69cobrajetrugae2]

Thank you. One more thing.  Are the T-10 transmissions considered good units?  I have read some negative reviews.

[CharlesTurner]

Thank you. One more thing.  Are the T-10 transmissions considered good units?  I have read some negative reviews.

Most prefer a toploader over a T10, synchronizer issues with B-W units.

[69cobrajetrugae2]

Thanks for your replies.  What grade transmission and rear axle fluid would you use?

[CharlesTurner]

Thanks for your replies.  What grade transmission and rear axle fluid would you use?

I use whatever the original shop manual calls for, can't remember, 75W90 or something like that.

[J_Speegle]

Used 80-90 wt Valvoline high performance oil yesterday. From what I've seen from the rebuilders no reason to over think the stuff or do anything fancy. These old time    transmissions were designed to use dino oils with no additives or fancy stuff

Of course if your using a Traction lok or similar rearend you'll need to ad the nasty smelling friction modifiers

[jwc66k]

Use 80W in general temperature conditions usually where it snows, 90W where temperatures get over 80F most of the time.
Jim