OK, My friend has a '74 Dart with 8 1/4 under it. It has 2.45 gears, and an open diff. He scored a dealer take out posie (clutch type) I think it is a track-lock with 3.91s out of a '97 Dodge Dakota. I know the splines are different but my question is: Can you buy and swap in side gears from an older 8 1/4 to make this unit work? Has any one done this? Or are we SOL?

I think that the 2.45 and higher(lower numerical) used a different carrier and will not accept any lower(higher numerical) gear sets,but maybe you could find a complete 2.76 or lower rear end and swap gear sets.
As far as swapping the side gears ,Im not sure.
HyperValiant

_________________
1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

YEs the 2.45 / 2.47 Axle has a different carrier. I Do not believe that swap will work - It will probably cause pain, headaches, butsted knucles and sleepless nights.


Greg

_________________
http://www.youtube.com/hyperpack

While this is being discussed, how much lower (higher numerically) can 8-1/4 gears go with the same carrier, if starting with 2.76:1? 3:55? 3:90? 4:10?

The 8-1/4 is in my '87 D150 if it matters.

Sorry for the quasi hi-jack.

-S/6

_________________
The "Silver Bullet"
87 Ram D150

Answer to question 1 in 500 words or less...

I believe Mopar Action had a 'tech editorial' on this once, and the conclusion was something like: you need a pre-95(?) carrier to match your axle splines...or find a machist to make a custom set....

Question 2: involves some of Question 1 so...

The 8 1/4" had a couple of carriers to work with ( your sure grip unit- I have heard of a 2.45 sure grip unit but never seen one...so mostly they are the 2.76 or better,the normal 'open'2.76+ unit, and the dreaded mileage 2.45/2.24 'open' unit)

The ring gears should work if you had the correct carrier for your axle for the ratio...

The 2.45 unit will not let you bolt anything to it except the 2.45 and 2.24 ratios.

The regular open carrier will let you bolt up anything from 2.76 on up (not sure how much fun a 5.83 open unit would be though).

So you can grab the gears from late carrier, buy a 2.76+ pre-95 carrier or new sure grip unit and get a kit, and have fun trying to make things work.

This is one of the reasons why the 8.75" is a nice rear...don't like the mileage out of your 3.91 gears...grab the 741 carrier with 2.76's out of a 66 fury and swap in about an hour... need to go draggin' swap 'em back...

-D.Idiot

OK maybe I typed it wrong so I will try to clarify. It is a 8 1/4 with 2.45 gears and an open diff presently. We have a 3.91 ring and pinion with a sure-grip out of a 97 Dakota. Can I buy side gears for a earlier 8 1/4 and swap them in to the carrier, and get this puppy set up. I would hate to see FREE go to waste.

Why would you need side gears if it's a posi? Are you talking about the spider gears that are in an open diff?

_________________
70 Dart, 360, 727

I am sure that for a couple of hundred dollars you could have some axles made up so you could use your "free" 3.91 and Sure Grip setup.

somewhere around 96-97 they changed the spline count by about 2.
8-1/4 posis show up on Ebag all the time for about $185. Sell your newer version and buy the older one. Or E mail some of teh sellers and see if theyd swap you. Seems its the same guys popping up with them.