Stomper

The gear ratio has nothing to do with the ring gear size . Every size rear end offers just about every gear ratio . Count the bolts on the cover . That will tell you which rear end you have without taking it all apart and actually measuring the ring gear . 8.8 has 10 bolts . 9.75 has 12

Old_Skl_Raptr

you wont have a 10.25. thats f250s and 350s axle. if you look at you diff from the rear, an 8.8 is O shaped and a 9.75 is D shaped. or you could count the bolts i guess haha

thump

I think they also used a 10.25 Sterling on the F150 HD.

Rick's 06

Hey guys thanks for the help. I was looking for a small project to do today and thought I'd change out the gear oil. I was surprised that it's about $70 to do this change. It seems like the only synth 74w140 was Mobile 1 or Royal purple with was $18 or $19 a quart. I also wanted to paint the cover while I had it off kind of like Tuna did. Anyway, since I wasn't sure how much to buy and it was a little more then I thought to do the job, I postponed it. I've only got 70K on the clock so it's not urgent. Manual says it's a lifetime oil, but I'm not buying it. When do you guys usually change your gear lube?

picaflor

i got my truck with 44k, and not even 50k now, i just replaced. i just want to be sure. i used lucas oil 70w140 which is also synthentic, it was like $10 each quarter.

Rick's 06

I saw some Lucas oil on the shelf, but didn't think it was synthetic. I'll probably knock this out next weekend now.

Old_Skl_Raptr

i think you may be right. but i consider 150 HDs a light duty 250 anyways. and if someones got a HD thayd probably specify

thump

agreed.. was just sayin.

Old_Skl_Raptr

^true dat.