Which transmission do I have, C3 or C4?

CharlieNH

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Jun 13, 2022
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I have been running my old Belsaw mill with a 1977 (I think) Mustang-II engine and transmission, and now I need to replace the automatic transmission's fluid filter. I don't want to take the old one out until I have a new one on hand, and I understand that this model with the V6 engine may have either a C3 or C4 transmission. Can someone kindly tell me from the attached pics or from any other method which transmission I have. Thank you so much.
 

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IICrew

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I believe it's a c4. The vacuum modulator faces out on c3 and rearward on c4.
 
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LILCBRA

I wish I didn't have all of these balls in the air
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Honestly, it looks like a C4 to me. The only way I know to tell for sure for transmissions that I'm not familiar with is the pan. Here's a diagram of the pan differences between a C3 and other transmissions of the era. It may help to count the pan bolts too, there might be more or less between the 2. Hope this helps!

1655205327331.png
 
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IICrew

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Mar 29, 2020
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Looking at pics online it's a c4. The C3 tapers where the bell meets the trans and the C4 has the pronounced waist line there.