89 Chevy rear end width

[bigbadjohn84]

Does anyone know if the 10 or 12 bolt rearends under the 73-87 chevy trucks are narrower or are the mounting pads just differenet? I am looking for a rearend for my 89, that would be around 2 in narrower, so that I can pull my 295/50 R15 deeper into the fender wells so when I drop it on down there won't be clearnce issues.. just want to avoid floppin down a grand or two just for shortening my factory housing and axles.. or would something like a ford explorer rear work? I am going to wind up loading the housing with Detroit True Trac and 4.11.. to wake up my 383 tbi I have built. but I want it LOW lol

[ChevLoRay]

You want it low, huh? How much lower in Alabama can you get and not be in Florida. I went thru your town, once.

If you don't get an answer pretty soon, I can move this to the engine/drivetrain forum. There's some knowledgeable folks over there, too. Only thing is, they're oriented toward drivetrains.

[bigbadjohn84]

yea man.. like 8-9 inch of drop over the rear and tuck those fat tires. thats the look I want. sorta a pro street look. loud, wide, and nasty. yea thats me, smallville Alabama lol. how do you move the post? that would be helpful

[Captainfab]

The '73-'87's are a couple of inches narrower than the '88 and up differentials. I have the exact measurements at the shop. I can look it up tomorrow and let you know.

[bigbadjohn84]

sweet!! thanks! I was wondering that. I knew some of the 73-87 I have had tucked 10 in wheels in the back with no issue. I just wanted to be able to tuck my 8 in wheels

[bigbadjohn84]

I measured my rearends. I have a 81 C10 2wd and a 89 C1500 2wd. the inside width, measured between the insides of the brake drums appears about a inch narrower on the c10. has anyone changed the rear out of an 89 in favor of the 12 bolt C10? I need it a little narrower so I can squeeze those 295/50 R15 up in the rear fender well.. any help would be appretiated

[Captainfab]

Originally Posted by bigbadjohn84

I measured my rearends. I have a 81 C10 2wd and a 89 C1500 2wd. the inside width, measured between the insides of the brake drums appears about a inch narrower on the c10. has anyone changed the rear out of an 89 in favor of the 12 bolt C10? I need it a little narrower so I can squeeze those 295/50 R15 up in the rear fender well.. any help would be appretiated

Just a little FYI.....that's not the correct way to measure a differential. You need to measure the wheel mounting sufrace to wheel mounting surface (WMS) This is where it matters.

The 10 bolt in my '90 C1500 measures 64 3/4" WMS to WMS

The 12 bolts in the '70-'80 C10's measure 63 1/2" WMS to WMS

The 12 bolts in the '63-'70 C10's (6 lug)measure 62 1/8" WMS to WMS

The '81-'87 10 bolts should be the same width as the '70-'80 12 bolts, but I haven't measures one to verify that. So there is a little info for you to work with to see what will work for your truck.

[bigbadjohn84]

hmm.. I have a 70 out in my pile of stuff.. but I guess I would have to get 5 lug axles beings its 6 lug. that sounds like it would be just right to tuck those tires like I want too. I'd have to change mount and all too.. but that's no biggie. I plan on flipping it to the top of the leafs anyways to make my drop. that would eliminate the need to purchase a flip "kit". just relocate my factory mount pads.. anyone done this? does it seem worth it? If I could find a custom offset wheel all this could be avoided. thats my whole issue. I am running a 15x8.5 wheel. I don't know what the backspacing is. it's a Ultra brand wheel, polished aluminum. looks like a rip off of the old Cragar Street star. I just love the look of those 295/50 under the back.. plus with my little stroker I built I need the meats along with a locker lol

[Handsome65]

Hi,

I have a 65 C20, and was thinking about swapping the Eaton semi floater out in favor of a Full Floater from a 2013 Chevy Duramax Silverado. I know the rear track of my Eaton, but not so sure about the 2013 full floater, and cant seem to find it on the internet. Does anyone know, by chance?

[b454rat]

9 year old thread, nice. It's wider, like 69".

[Handsome65]

Originally Posted by b454rat

9 year old thread, nice. It's wider, like 69".

yes, I know it's an old thread, but it seems to be relevant to my question so I figured it was as good of a place to post as any. That said, the rear track of my 65 C20 is 67 in, so if the other axle is 69, that's pretty close, I think. Anyone disagree?⅝

[Jaybob]

I know this is an old thread but I am interested in this topic. Have been looking and measuring and I swear the the 73-80 12 bolt is narrower than the 81-87 10 bolt. As far as I can tell the 73-80 12 bolt is 63.5" axle to axle or 63.75" WMS to WMS. The 81-87 seems like it is a little wider at 64.25" axle to axle or 64.5" WMS to WMS. I have measure my 78, but I don't have a square eye square body to compare to. I am building my own 15x11 rally wheels and fitment and backspacing choice is crucial. It looks to me that you would need different offset as they are different by 3/8" per side.

Anyone else have verified 81-87 2wd 10 bolt rear axle widths?