8.25 10 bolt Imposter

Roadrunner360

Roadrunner360

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I was under the impression that if your differental cover had 10 bolts it was identified as a 8.25 rear. If you had 9 bolts it was a 7.25 rear. Well, I ordered new a new cross pin and bolt for what I thought was an 8.25 rear only to find out it is a 7.25 rear. When I recieved the cross pin and bolt they were the wrong size. So I pulled the axle and counted the splines to confirm and counted 25 splines confirming the 7.25 rear. I thought all 10 bolt rears were 8.25. Anyone ever seen this befor? A 10 bolt rear 7.25 am I missing something? .......Joe.....please say it ain't so!

I am now in the market for an 8.75 rear.......as it now turns out.........:pottytrain5:
 
The 7.25 rear has tapered axle tubes where they meet the center housing.
The 8.25 rear has straight axle tubes.
 
Here's some quick referance for ya....

mopar axle.jpg
 
I had heard that there could be 10bolt 7.25. I think the difference is still in the cover. The 8.25 have oval covers and I believe the 7.25 are not. I am not sure if the 10 bolt 7.25 have tapered tubes.

Kevin
 
I know that the 8 1/4" rear ends with 2.45 gears used a different case. But the covers were 10 bolt and the same oval cover.

Image.jpg
 
bremereric said:
Here's some quick referance for ya....
Click to expand...


Thanks for the info all! My rear axel cover doesn't look like any of the ones shown here. I will take a pic and post it here. Thanks for all the help!

I am really disappointed.....not only is it a lowly 7.25 it is also an open rear end. I should have done some better research. I thought it was pretty simple to identify 10 bolts 8.25......Wow! I feel really stupid!:hiding:
 
You got me with this one... I've never seen a 10 bolt 7 1/4 ever. If the car your working on is the one in your avatar, I don't get why it would have a little 7 1/4. All the V8 f bodies I've owned have had 8 1/4's in them. Was it swapped? Can't wait to see these pics.
 
Wagonmaster said:
Later model 7 1/4's are 10 bolt. I pulled one from an 87 Fifth Avenue. 2.24 gears and all
Click to expand...

It must be a swap. Interestingly the gear ratio tag says a 2.2. This gives me even more reason to believe this was a swap. Must be a direct drop in, cause it looks factory.....to me.

IMG00016-20110528-1830.jpg


IMG00021-20110528-1840.jpg


IMG00016-20110528-1830.jpg


IMG00021-20110528-1840.jpg
 
Id say it was a swap. The one I had went into an 80 Volare Duster. I think most of the later light duty 318 cars got the 2.24 gears also.
 
I learnt something new today.That's the first one I have ever seen. I must be stuck in the 70's man.
 
I had never seen one either but heard they were real, I think they were all in the 80s. But definitely a different cover than anything else.

For the 2.45 and 2.2 ratios of the 8.25, the cases are the same, the carriers are different. I have a 2.2 suregrip to replace the 7.25 in my 77 aspen R/T and want different gears. I now need to find a new carrier and gears. I found out that i can find what i need in any 8.25 up to 1996 so I will be going to a u-pull it and find a dakota Ram or van with a sure-grip cheap to get the carrier and gears.


Kevin
 
Thanks for all the help! If i decide to change this out to an 8.25 or 8.75 what doner cars should i be looking for or where can i by a complete set up (sure grip included)?

Thanks again all........and a happy Memorial Day! Hooah!
 
Roadrunner360 said:
Thanks for all the help! If i decide to change this out to an 8.25 or 8.75 what doner cars should i be looking for or where can i by a complete set up (sure grip included)?

Thanks again all........and a happy Memorial Day! Hooah!
Click to expand...
just like Kevin said..."I found out that i can find what i need in any 8.25 up to 1996 so I will be going to a u-pull it and find a dakota Ram or van with a sure-grip cheap to get the carrier and gears."
 
I would think a 8 1/4 out of a '80's M body cop car would be the easiest swap. If I'm not mistaken, they had 2.9 gears and a sure grip, but the M body guys could tell you for sure.
 
I got my 2.94 sure grip from an 83 police car. Most of the cop cars had the 2.94 but not all had the sure grip. The cop cars are suppose to be a little stronger but they were also abused a bit more
 
The cop car that gave up the 8.25 rear I have must have been a cruiser as it has A 2.2 Suregrip in it. That is why I need a different carrier and gears as my suregrip carrier will only take the 2.2 and 2.45 gears. I would prefer 2.94 or 3.21 gears.

Any diplomat gran fury and 5th ave 8.25 rear fits our cars.

Kevin
 
77RTNJ said:
The cop car that gave up the 8.25 rear I have must have been a cruiser as it has A 2.2 Suregrip in it. That is why I need a different carrier and gears as my suregrip carrier will only take the 2.2 and 2.45 gears. I would prefer 2.94 or 3.21 gears.

Any diplomat gran fury and 5th ave 8.25 rear fits our cars.

Kevin
Click to expand...

Kevin, what years of Diplomat Grand Fury and 5th Aves should I be looking at?

Thanks All! I appreciate all the info. I believe my plan of attack will be to repair what I have and enjoy the summer....while at the same time look for a complete 8.25 (sure grip) rear with axels and drums. 8.25 will be more than enough for me....... anyone got one just lay'n around take'n up good usable work space????

Again thanks to all of you that responded! Beware of 7.25's wearing 8.25 attire.......they are among us!
 
Roadrunner360 said:
Kevin, what years of Diplomat Grand Fury and 5th Aves should I be looking at?

Thanks All! I appreciate all the info. I believe my plan of attack will be to repair what I have and enjoy the summer....while at the same time look for a complete 8.25 (sure grip) rear with axels and drums. 8.25 will be more than enough for me....... anyone got one just lay'n around take'n up good usable work space????

Again thanks to all of you that responded! Beware of 7.25's wearing 8.25 attire.......they are among us!
Click to expand...
Look at any model year 1981-1989...my 1981 Gran Fury has one in it that is pretty much a direct bolt up to my F body
 
Road runner,

Any FMJ car (aspen, volare, lebaron, diplomat, gran fury, caravelle, etc.) up to 1989 is a direct bolt in for the housing. If you can find the 8.25 housing out of those cars, you can swap in any suregrip from the 70s up to 1996 out of any vehicle with an 8.25. After 1996, the axle spline count changed.

You should get at least a 2.76 gear ratio in the suregrip, so that you can swap in any gears, lower than that the carries don't accept the higher gears.
I did not know that when i got my 2.2 suregrip, so now I need a different carrier.

Kevin
 
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