Hi guys;

My name is Charles and resides in South Africa.

I recently acquired a 1978 Ford F100 Custom SWB. It has a 351cu Cleveland with a C4 3 speed auto box.

I am bust restoring and customizing my pick up and was wondering if anyone can assist or have an idea of what my rear axle assembly ratio is.

I have tried searching for it and the only problem I have still is identifying exactly what the ratio is on my rear axle as I cant find any reference to the following:

9E21 AND THEN THERE IS ALSO A NUMBER OF 22 BY ITSELF

The following I could get from it:

9E21 C5AW 4668A 22 DIF

 

Did you get that sequence from the metal tag attached to the axle on one of the bolts? None of those numbers look familiar to me anyway. The other way to do this is count the tire spins compared to the drive shaft spins.

 

Those are the casting numbers from the 3rd member case and pinion support.

If the I.D. tag is missing off the 3rd member, the axle code will be on the drivers side door jamb tag.

 

Thank you guys;

Unfortunately the only tag I did find was located in the engine bay ten to relocated to there. From what I got from it was that the rear axle code is A. Checked it and what I managed to find was that it is a 3.5:1 ratio as per the guide I found for African build Ford Pick ups. I did a test as well by jacking up the one side and marking the prop shaft and tyre. Turned my tyre 10 times and my prop shaft turned 15 times. 15 X 2 devided by 10 gives me a ratio of 3. Close enough to the 3.5 I suppose.

 

Hi Charles.Not sure I understand your explanation. Possibly leaving the right tire ground with an open-differential might skew the result??
If you jacked-up the rear (both tires,) and you turned your tire 1-revolution, the driveshaft wouldspin 3x exactly for a 3.00 ratio, or 3-and-one-half turns for a 3.50 ratio. (10-revolutions of the tire would net 10xthose numbers … 30 or 35 driveshaft revolutions. Note with an open-diff the tires will turn in opposite directions.) A 3.00 vs 3.50 ratio is significant, and it should be obvious with only one tire revolution. Good luck!

 

Trucks sold new in South Africa, Australia/New Zealand use a completely different VIN, codes stamped on the Warranty Plate...and where it's located, I haven't a clue.

9" rear axle tag located at approx. 5 o'clock under one of the bolts that retains the carrier (pumpkin) to the housing. By now, many of these tags are missing.

Notice it has a 351C. In the US/Canada, 351C's were only installed in 1970/74 Ford/Merc Passenger Cars and Ranchero's.

But in South Africa/Australia/New Zealand, 351C's were used for many years in both cars & trucks.

 

Thanks for the advice. I will jack up the axle to ensure both wheels are from the ground and test. With the initial test with only one wheel in the air it resulted in the prop shaft only turning 1 and a half time for one full wheel rotation. Will keep you posted after I tested it with both wheels lifted from the ground.

 

Yes sir. There was also an Australian Cleveland 302 in addition to the 351 Cleveland.

Cleveland -- The Ford V-8 Engine Workshop