[mojonelo117]

hey guys i have a 79 ford shortbed pickup. i dont know anything about rear differentials but i need to know what kind it is, what gears (if possible) and recomendations to get the most bang for my buck.

[Deuce]

WELCOME to Hotrodders.com

Most Ford pickups of the year had the 9 inch Ford rear end ...





It should have a tag ... similar to the one shown ....
find it, read it and then look here ... to find out what the ratio is ...

http://www.fordification.com/rearends-ford.htm

Get back to us and let us know what ratio you have
and again WELCOME ...

Deuce ... Moderator

[xntrik]

Probably a 9 inch Ford. The "gear assembly" bolts are on the driveshaft side of the housing. Under one of the bolts will be a metal tag. There are two lines of numbers on the tag. Next to the bolt itself on the bottom line will be 3 numbers. Often the first number is covered by the nut. Probably 3 00 or 3 25 denoting the gear ratio. If it has an L, like 3L00 that is a 3.00 limited slip (posi). The next "9" tells us 9 inch ring gear. After about 1970 the tag format changed to include the ring gear diameter after the ratio.

The bottom line would look like this...... 3 00 9 D479..... the last four are irrelavent.

The top line will consist of letters...like........ WFZ-AB or something like that. That is the axle code in the parts books and decoding gives info like which vehicle and year it was originally installed into. You can google that number.

edited:
If your tag is missing, a nine inch differential is identified by looking at the lower two bolts/nuts below the driveshaft holding the assembly into the housing. A nine inch differential requires an end wrench on those two nuts since a socket cannot fit. The only other way to check gear ratio is to turn one wheel (only) one revolution while counting the revolutions of the driveshaft and multiplying that by 2 = ratio. If it is a limited slip it will be reluctant to turn the rear wheels at different rates, so turn them both equally one full turn and count the driveshaft revolutions for the specific ratio.


http://www.kevinstang.com/Ninecase.htm
You will see that the tag indicated in the above post is for a 60s eight inch differential. After about 1970 the tag format changed to include the ring gear diameter after the ratio.

www.readershotrods.com

[mojonelo117]

thanks so if i wanted to change my gear ratios what would you best recomend and why(im not planning to drag or go of road i just want it to be fun to drive, or at least be able to peel out )

[xntrik]

We still don't know what you have as per existing ratio and tire diameter, so it is very difficult to make any recommendations.

Take whatever gear you have and add .50 to it........ example 3.00 + .50= 3.50.... that ought to help with spinability without killing the highway rpm.