ok so i have a 66 fury 2 four door sedan it had a 318 poly in it i took out the 318 poly and tranny and put in a 383 and 727 tranny now i have no idea what rear end i have but it does not have positraction only one wheel spins and it must have highway gears cause even with the 383 you cant peel tires if it helps i counted the bolts on it and it has 10 bolts .......... now my question is what rear end do i have? what gears do i have? and what gears do i have to get to make it quick off the hop? i want positraction or in other words sure grip ...please help me!

 

On a 66 my guess would be that it has a 8 3/4 Does it have a rear cover or unbolt from the front ?

 

With the 318 Poly, I would guess 8.25 rear with something like 2.73 gears. Take a look at this pic as it may help out.



What mods have been done to the 383? The 8.25 can handle a stock 383, even with some mild performance parts. If you want something that will really make it getup and go then throw in a sure grip and a set of 3.55 or 3.73 gears. You'll still be able to cruise down the road without revving the **** out of the motor but you'll feel the get up and go a lot more.

 

ok it does unbolt from the front it looks exactly like the 8 3/4 rear end i guess thats what it is thank you........ now the 383 has headers it has an edelbrock rpm intake and a 650 holley this winter i will put a comp cam in as well as a 750 holley so what gears do you reccomend and where do i find them?????

 

The 8.75 rear axle is pretty strong. I'd say go with a set of 3.55 gears as they will still aloow you to drive on teh highway but you can still get on it when you want. I'm sure others will give some suggestions too.

I prefer Richmond and Yukon ring & pinions but everyone has their own preferences. You can get them at just about any online speed shop.

 

ok so what do i buy? 3.55 gears rings and pinions? and then how do i get suregrip? sorry i know nothing about rear ends

 

If the rear has not been molested ? There will be a tag under one of the differential bolts with the gear ratio listed. I would guess 2.91 or 3.23 maybe. If you have no differential experience I would look for a good used one $400-500 or $1000-1400 for a new reconditioned one ready to install..

 

This here is what you are looking:
http://www.ebay.com/itm/MOPAR-REAR-8...983741&vxp=mtr

If you want to get all new parts then you first need to see what case you have and go from there. Lets say you have a 489 case, here is a list of parts that you would get -
3.55 R&P: http://www.summitracing.com/parts/RMG-6903711/
Install kit: http://www.summitracing.com/parts/RMG-8310311/
Sure grip: http://www.ebay.com/itm/Mopar-8-75-8...88200f&vxp=mtr

If you have no experience doing this kind of work, I suggest looking around your area for some speed shops and/or some axle/drivetrain specialty shops that can do axle work (and are known for their axle work).

 

Unless somebody changed out your 8 3/4 for the larger pinion you would have a 741, or a 742. The large pinion 489 case didn't come out until 1969. If your car is a factory big block it has a 742. Small block cars used 741. The 741's are hard to find parts for since most racers, hot street guys use ether the 742 or 489 pinions. I hope this helps you. Jason

 

ok does this mean i can pull the center piece out wich doesnt have posi and buy the gears and stuff and make it a 3.55 with posi? or do i need to buy a new one?

 

and also what cars had these kind of third members in them cause id even try to find one at a salvage yard

 

Yes you can rebuild the unit you have in there now with what you want. Just make sure that you order parts for the right case as there are 3 different cases like 68plymouth383 mentioned.

Whatever you get from a salvage yard would probably have to be gone through. I'd rebuild the one that you have.

 

Ty Henry: I see rebuilt 3rd members for 8 3/4 differentials fairly often on Craigslist out here in the SF/Bay Area. Some are Suregrip some are not but, it's worth a look in your area...

 

All I saw was Furry Rear End Please Help!

Thought you were on the wrong forum for a minute there!

Fury, ok now I get it! LOL!

Tom