ok, so long story short, the shop said my pinion bearing is shot. i'm going to get a second opinion but i'm not hopefull. they said that this means that my gears are probably shot too, so i might as well rebuild the whole differential. that would cost $1200. i thought it might just be cheaper to get a whole new axle from a junkyard. i have the 8.8" and i was wondering if there was any benefit to swapping to the 9.75"? i have been searching but havent found much good info. i know i will have to get a driveshaft too, but does it have to be off the same transmission as mine? also, am i gonna have to use the brakes off the new axle or can i use my current ones? i know that switching to discs is going to be a pain. also, i was hoping to eventually replace the leaf springs with some beefier ones of another f150. would i HAVE to replace the springs or can i hold off on that? thanks in advance!

 

the leaf springs will be ok that you have now. you can actually have a driveline shop professionally shorten your rear driveshaft. the swap is as direct as possible, everything will line right up.

you would be better leaving the brakes that are on the new axle on there. switching to discs isn't as bad as you think, just do a search on the topic. drum brakes suck, especially when it comes time to service them, lol.

 

The axles line right up. When I did mine I had the drive shaft shortened. The easiest way I found to measure the amount to cut was to remove the drive shaft and measure from the pinion flange to the output shaft of the transfer case, in your case the transmission. Do this with the truck on the ground. Then install the 9.75 and measure again. The difference in the measurements is what has to be cut off. In my case a bit more than 1 inch.

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thanks for the replies. i think i am going to stick with the drum brakes even though they suck because my parents are paying for the axle and i am about to become a poor college student so money is kinda tight. i would rather just remove the existing drive shaft off the donor truck if i can because my parents are really strict about my truck and i dont think they would like it if they knew i was getting a different type of axle. i know, its kinda weird how strict they are but i think i can sneak it past them this way. also, i assumed that the 9.75 was stronger and thats why i'm upgrading. this is true, right? and thanks for the help.

 

YES, the 9.75 is a way, way stronger axle. Lightning guys have put like 800 hp through them, and the axle holds up just fine. just so you know, 97-98 9.75's came equipped w/ drum brakes, so that gives you an idea of where to start searching...

 

ok. thanks. just one more thing, will the drive shaft off the donor truck bolt up directly to my transmission? and i assume that i have to get an axle with drum brakes even though i am going to use my brakes off my current axle. now i just have to look up the axle codes. hoping to get a 3.73 l s diff. maybe my luck will turn for the better now. lol

 

don't be too picky on the ratio. few 97-03's came equipped from the factory w/ the 3.73 ratio. personally, in your shoes, i would search for a 97-98 9.75 w/drum brakes, either 3.55 or 3.73. i don't think the drums off of your current axle will work, either. you'll need a complete axle.

driveshaft length is controlled by many factors, including cab/bed configuration, engine, transmission, rear axle, etc. i personally feel you would be better off professionally shortening your current driveshaft than trying to find one of the correct length that will bolt up. just an FYI, 1 1/4'' of slip yoke is supposed to be sticking out of the transmission. too much sticking out could lead to the driveshaft falling out, and it being too far in could result in transmission destruction over a hard bump.

 

ok. thanks. well, i wasnt going to be all too picky about the ratio. i would settle for either a 3.55 or 3.73 but it HAS to be a limited slip. thats one thing i wont compromise on even if it means going with a 8.8" rear end. my little 2wd need as much help as it can get. and i'll be sure to get the drums and have the driveshaft shortened. thanks for all the help. i should be going to the junkyard early next week. i'll be like a kid in a candy shop. lol

 

I would never buy a junk yard drive shaft. I would also strongly recommend the pros shorten yours. Most of the used drive shafts have been manhandled and abused. At the very least you would have to have it inspected for balance and new U-joints installed. You know the condition of yours so there will be no surprises there.

Regards

Jean Marc Chartier

 

ok. good point. one more quick question. how can you tell the difference in a 8.8 and 9.75? i know most of the 5.4's will have the 9.75 but i wanna know a way to know for sure that i have got a 9.75. and do say something smart like "one is 8.8 inches and one is 9.75." lol

 

Once you have seen them side by side you can not ever mistake one for the other.

8.8


9.75


.

 

ok. thanks. i thought thats what the 9.75 looked like but i just wanted to make sure i didnt mistake a 9.75 for a 10.25. i've done all my homework on swapping to a 9.75 and didnt want any unpleasant surprises that i wasnt prepared for. lol. thanks everybody. i called the mechanic that i'm going to be "helping"(he's gonna come to my house and i imagine i'll end up doing most of the work. lol) and i'll be starting working on it as soon as i can find a new diff. the bad news is that he said the shop that'll be shortening my driveshaft will take 2 or 3 days. well, looks like i'll be without my truck for a couple days. : /

 

one more question. how do you remove the driveshaft from the tailshaft of the transmission? i know i can unbolt the side near the differential. i can see the bolts there, i'm just not sure how to get it off near the transmission.

again, thanks for all of your help. i like knowing whats in the puddle before i step in it if you know what i mean. y'all have given me tons of invaluable information and i dont think i would be willing to start the swap if it wasnt for your help. thank you.

 

It slides off. Expect oil to drip out. I use a baggie and duct tape to seal the hole.

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ok. thanks. looks like i'm ready to get started. now i just have to find a diff. i'll post up how it went.