Hello, I am about to purchase a 1956 f100 and import it (hopefully).

A guy over here was asking me if the truck's rearend had been swapped for a more "car like" one with better gearing ie top speed 100+ (instead of 70) and better MPG.

The ad said:
It has:
302 V-8 4 Barrel
C-4 Automatic
Ford 9" Rearend 3.25 Posi


--So is a 9" 3.25 posi "more car like"?

Thanks.

Here's the pics:
http://picasaweb.google.com/Quiff.boy.elvis/F100/

 

Ford started putting their 9" rear axle in both cars AND pickups in 1957, so the change is not drastic and most would consider it an improvement. The car and pickup axle housings were slightly different. The pickup used equal-length axles and the differential carrier was offset to the right because of this. In passenger cars the differential carriers were centered, partly because clearances were tighter with the floor hump. This meant that car axles are two different lengths.

Which ever you have, I would leave it alone so long as it works well. It is a nice setup, with many parts and options available.

 

thanks for you help. what would you guess the top speed would be with a 302 and a 3.25 posi?

 

Using a 29" tall tire, @5000rpm with a 3.25 gear will get you about 132.8mph.
Here is a good tire size/gear ratio calculator https://www.ford-trucks.com/calculat...mph_rpm/a-mph/

 

Okay. the rears are P235 70R15 apparently. Any ideas if they'd be 29" tall?

Cheers,
QbE

 

skip that, I've found:
1. I have incorrectly quoted the fronts --the rears are actually P255 70R15
2. and they are 29"


See http://www.mickeythompsontires.com/tech.php?bulletin=s9

Thanks for all your help.

Cheers,
QbE