how to tell a c4 from a c5 trans

[CanyonGT]

i just got a fairmont factory v8 smallblock trans and i think it's a c-4 but not sure what year it came from. i do know it was a wagon. so i need to know how to tell a c4 from a c5 trans. i can get pic's and casting numbers if needed just mite be a day or two. thank's guys matt.

[JACook]

One easy way is the C5 uses a fine-threaded secondary band adjusting bolt. The adjusting
bolt on the C4 is coarse thread. Both C4 and C5 use a coarse thread for the low/reverse
band adjuster.

The C5 also has a deeper pan, and larger cooler line ports. If you remove the pan, you'll see
the C5 has an additional smaller valve body casting piggy-backed on the main valve body.

Mustangs began using the C5 in 1982. I don't believe the Fairmont/Zephyr ever did.

[Greywolf]

Actually, the C5 started in '82. There may have been some 255 V8s with the C5 but by the time the C5 was in production, the F/Z cars weren't available with the 302 anymore.
I'm pretty sure the C5 was used in place of the C4 on the 200-I6 in late 81+; I think that may have been part of the reason for the "big bell" inline-6 casting.

[CanyonGT]

okay thanks guys. i did find a part number on the bellhousing starting with d7 meaning 1977. if this helps. but i'm pretty sure it is a c-4.

[JACook]

I'd say you're right. One final check would be to measure the bellhousing depth. The
large 164-tooth C4 bell is 6.25" from the block face to the pump face. The C5 bell is
3/4" deeper.

[CanyonGT]

okay thanks that confirms its a c-4. thanks a bunch guys.