Customs Either or ?

I have a 351W to go in a '51 Ford.
I also have a C4 and a C6 transmission.
Question is ... which one to use.
C4 is 1967.
C6 is mid '80's.
Thank you for any information.

 

C4 is an easier fit

 

Isn’t the C 6 more heavy duty ? I would go with heavy duty

 

Do you have the parts necessary to get either of them to bolt to the engine? ie flexplate, block plate, converter?(C4 changed input shaft in 1970, so might be more challenging to find the right converter)

what condition are they in?

Have you looked at how much room is available for the transmission? and what the crossmember situation is? and the driveshaft?

C6 is more heavy duty, the C4 can be built to handle the torque but that might cost more.

Not a simple decision, as I see it.

 

As I understand, the later C4 is a better choice than the 60s version. Not sure all C4s will fit a 351, but I'm no expert. The C6 is much bigger, and uses a lot of HP. You can do it, but a later C4, or AOD might be better.

 

The c6 is stouter. But eats more hp, heavier and takes up more room.
C4 s are stout if ya spend some $$ on em
For a daily cruiser, I’d prefer the c4
For a truck thats used like a truck, I’d use the c6

 

It looks like I'll go with the C4 then.
I'll have it looked at to make sure it adapts.
Thank you for your input.

 

I have a 1957 Ford 2d Hartop w 351W 80's F150 block with a C4, it runs just fine.
I would check tunnel clearance.

Also if you can AOD it, it would be best.

 

Neither [Sell them both]
Put an AOD behind it

 

I removed my C4 from behind my 351W and installed an AOD. I am running a 3:50 gear rear end with tall tires and at 70 mph, I'm only turning 1700 rpm's. It took a lot of punch out of the motor when in 4th gear. I have 3:70's to install but you will want a higher stall converter also. This is where I'm at.

 

The C4 would be a much easier fit and unless you are going to beat the snot out of it, will be fine.

1967 was the first year for "select shift", which means in the drive position, the trans will start out in 1st gear, shift to 2nd and 3rd.

Downside is the early C4s had a 24 spline input shaft. Later is 26 spline.
Finding a torque converter becomes somewhat harder and selection limited.