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I just pulled the diff. tag off of my '73 f-100 2wd parts truck. I want to swap the rearend into my '79. I'm not real sure if its a 9" or 8.8" and was wondering if someone could decode this for me.
WDM AC 3DB
3 25 9 331A
I kinda hoping its a 9" if not oh well. Appreciate any help anybody can offer.
It appears to be a 9 inch by the location of the 9 in your tag. And the gear ratio appears to be a 3.25 to 1. As far as telling for sure that it is a 9 inch and not an 8.8 is by looking at whether the pinion looks like it is going into the bottom left as opposed to the center on the 8.8.
The 8.8 will have a rear cover and the 9 inch you can pull the complete third member from the front of the housing.
To pull the axle you need to remove the 4 bolts inside of the drum which look like they are holding on the backing plate. The axle may need a little help coming out. You can hit the backing plate with a hammer to get the axle to come out. If the axle will not come ot that way then you will need a puller. Don't beat the backing plate to death unless you have spares lying around.
Be careful because the F100 could be a 28 spline set up and your F150 should be 31 splines.