289 5 bolt or 6 bolt?

I am doing a tranny swap to a T-5 from a C-4 and the articles I see tell me that early 289's in mustangs were 5 bolt and later changed to 6 bolt. I am not sure if this is the original block so I don't know which it is. I am gathering parts and would like to be able to tell which block plate to purchase. Is there any way to tell which block it is without pulling the tranny? Thanks.

Count the # of large headed bolts that pass from the bellhousing into the motor block. That is what the 5 or 6 bolt thing is referring to. Also, another indicator is the diameter of the bolt--if the bellhousing to block bolts have a 5/8" head, you have a 6 bolt block. If smaller, you have a 5 bolt block.

Disregard the starter bolts and the small bolts that retain the inspection plate.

Originally Posted by blidzy

I am doing a tranny swap to a T-5 from a C-4 and the articles I see tell me that early 289's in mustangs were 5 bolt and later changed to 6 bolt. I am not sure if this is the original block so I don't know which it is. I am gathering parts and would like to be able to tell which block plate to purchase. Is there any way to tell which block it is without pulling the tranny? Thanks.

64 is the year (more or less) that Ford changed over from 5 bolt to 6 bolt blocks. If you know how to read block date codes, that will be a great indication of when the block was cast.

Other than counting bolt holes, thats the best way, cause as I keep mentioning, not all motors are original to the car they came in - people/mechanics, dealers were more concerned with getting car running rather than wasting time looking for an 'exact' replacement engine.

You guys rock. Thanks.

Originally Posted by dennis111

Count the # of large headed bolts that pass from the bellhousing into the motor block. That is what the 5 or 6 bolt thing is referring to. Also, another indicator is the diameter of the bolt--if the bellhousing to block bolts have a 5/8" head, you have a 6 bolt block. If smaller, you have a 5 bolt block.

Disregard the starter bolts and the small bolts that retain the inspection plate.

It was a 6 bolt. Hooray. Thanks again, saved me pulling the thing and then ordering parts.