What kind of car / differential?

I don't really see how you can just change out pinion bearing(s) without removing the diff carrier bearing anyway. So you should just be talking about the additional price of the two carrier bearings.

Unless you are talking about rebuilding the entire rear axle, to include the axle bearings.

BTW, I just moved to St Charles, IL. Where are you haveing your work done?

 

65 FB w/4spd, and i am embarrassed to say I don't know what diff is in the car. I'm having the work done at Sparks in south Naperville. Not a place that I would recommend, I just needed to get it done before I put it away.

I can however recommend Mustang Restorations in Dundee IL. Not too far at all from St. Charles. A+ work.

 

Are you wanting to change the gears as well or are you happy with your current set up? Now is the time to figure it out. A rebuilt center section will cost the same (around $900) and will bolt right in- can get any ratio you want. Of course you'ld want to check the axle bearings (I'd just change them while it's apart) and axle seals. I just went through this- changed to a 3:55 tru trac, new axle bearings, seals. Took one afternoon (borrowed a slide hammer from auto zone). John

 

I was fine with the gears, It was just making a lot of noise.

 

I just referbed a 8" rear end, $1100 parts and labor, and it has a Auburn LSD in it.

 

65 FB w/4spd, and i am embarrassed to say I don't know what diff is in the car. I'm having the work done at Sparks in south Naperville.

Assuming your '56 came with a V8, it probably also came with an 8" differential. Only the HiPo289 cars came with a 9" in that year.

You should probably ask a few more questions. I really don't know how you could change just the pinion bearings on that differential, without doing the carrier bearings at the same time. And thats really all there is to a total rebuild on an 8".

Could it be that they are including the axle bearings on their 'total' estimate? If so, $350 is a pretty good deal on a diff rebuild.

I would just be carefull. I would not trust most shops to rebuild my differential. You should deffinately make sure they know what they are doing.

 

Assuming your '56 came with a V8, it probably also came with an 8" differential. Only the HiPo289 cars came with a 9" in that year.

You sure about that? Everything I've ever heard or read the last 30 years has said that the only Mustangs to get 9" rearends in 1965 and 1966 models were Shelby GT-350's. 9" rears didn't show up standard on Mustangs until the 1967 model and then only with 351ci or larger engines. Boss 302 Mustangs being the exception to that rule.

 

I wouldn't recommend it either, but I'm sure there are some shops out there that would do it in the interest of making a buck. There are plenty that will replace a pinion seal without replacing the crush sleeve and just just an air impact to hammer the pinion nut back on. There's quite a bit of difference in the amount of labor involved, but you are correct - the right way to do it is to pull the whole thing apart and check all the measurements. That's the way I would expect it to be done. Not sure how many labor hours would be charged - probably at least 5? If that's the case, most of that $350 is probably labor - parts for that job are probably $30-$40. I was just pointing out that the pinion bearings "could" be changed without disassembling the whole rear end, even though it's not the right way to do it.