I learned today there is a difference in 9.75 differentials , 1999 and earlier are slightly different than 2000+.. pinion bearing size maybe? didn't really get an answer from Randy's R&P Is there a way to tell the difference without pulling the pinion and ID'ing the pinion bearing ? I'm considering 4:56's and they are not available in the 1999 and earlier.

My truck was built in October 1999, it's possible it got the upgrade.

 

Look at the axle code on the door jamb sticker. Then google it.

Identify Your Ford Truck Axle From The Door Sticker : Blue Oval Trucks

 

There are numerous different rear ends that were used on the yr 2000 model trucks. Different gear ratios with different carrier/tube configurations...each with their own unique identifier. 4:56 gears are not and were not standard on any F-150, F-250, F-350, F-450, or F-550 that I can find. I haven't checked F-650's or the 700's or 800's.

Is there by any chance a sticker on your axle tube that will help identify it?

For example, stock 3:31 R&P ratio would have the sticker with either SD916A, SD916B, or SD916C on it, and each carrier/tube combo would be specific for either rear drum brakes or rear disc brakes.

3.55's: S918 D, E, or F <or> S919D, E, or F <or> S933P <or> S941A, <or> S942A (drum or disc for each option) <or> V918A, V918B, V919A, or V919B with disc brake configurations only.

3.73's are identified with S923D, E, or F with either drums or discs.

Those are the only options for stock replacement rear ends for a 2000 F-150. F-250's are slightly different and the same goes for F-350 etc.

Does that help some or does it just muddy the waters? If your truck has a build-date of 10/99, it is included in the 2000 year model truck line.

 

Is there a metal tag with numbers under one of the differential cover bolts? If so post the numbers and we should be able to help you ID it.

 

he has a 9.75 inch rear end........ problem is it is a 1999 ....... in 1998 there was a SMALL PINION bearing... in 2000 there was a BIG PINION bearing.... 1999 was the change over at some point.

 

^^^ this is correct, but without pulling the pinion seal and getting getting the pinion bearing number according to Randy's RP I can't get 4:56's for a pre 2k 9.75 RP, so until I find another way to ID the differential I won't be regearing too soon.
Hope that makes sense.

 

Mickey, do you have a micrometer? You can try measuring the pinion output shaft and I can try to match it up to known parameters...I've got tons of 9.75's on my yard.

steve(ill), who's the member on here who specializes in all the Ford numbers? I've seen him on some of the other boards and his knowledge base is pretty amazing. Any chance he would be able to help with all of this?

 

@NumberDummy

 

Interesting, I'll see if I can get a message to him and I'll report back.

Thanks again for your help.
Mickey

 

Just tried to pm numberdummy, he either cannot receive PM's or chooses not to.
ill look around for a thread he answers and maybe get him that way..
Thanks guys

Mickey

 

He (NumberDummy) is very active in the 73-79 forum. I would wager his inbox is full and cannot receive any more messages.