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GenII Dakota
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Discussion Starter · #1 ·
I've been wanting to have a posi put on my truck and I was wondering instead of ripping one off an old car or something, could I just buy a posi unit and use my existing axels? Whatever I use, I'll need a solid unit that could hold up about 500 HP. This truck will be used at the strip every now and then but why gears should I go with for one that will be mainly used on the street?

Thank you,
-Jason
 

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There are many considerations when deciding on an appropriate gear ratio. The main considerations are: Intended use (where will the truck spend most of its time) and tire size. If you spend only one weekend per month at the drag strip, then I'd stick with 3.55's or possibly jump to 3.73's. If you intend on racing the truck more than driving the truck, consider 3.92's or even 4.11's. But forget about highway driving with 4.11's because, if you're like me, you won't be happy stopping at each and every gas station between you and your destination.

I've got a friend who tows a 24' travel trailer with his 2000 Dakota quad cab. He has 30" tires and traded his 3.55 gears for 3.92's. The guy can't stop raving about his towing capabilities. On the flip side, he also can't stop raging about his poor gas mileage. My 2000 Dakota, which I traded it for a 2003 Ram with the Hemi, had a posi with 3.55 gears. It had the 4.7L engine and 275/55 R15 tires (about 27" tall). The truck ran 16.2 at the local drag strip and got close to 18MPG on the highway. However, my Ram has a posi with 3.92 gears and 305/50 R20 tires (about 32" tall). This truck runs 15.2 at the strip and gets close to 14MPG on the highway. For comparison sake... my Step-dad has a hemi ram with 3.55 gears that consistantly gets 18MPG on the highway.

Just some things I would consider:)
 

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GenII Dakota
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409 Posts
Discussion Starter · #3 ·
I'll probably stick with 3.55 or possibly 3.73.. because this truck would only be used about once a month (if that) at the strip... I need a strong unit though.. would I be able to use my existing axels or would they have to be upgraded as well.. and how hard would that be?
 

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GenII Dakota
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409 Posts
Discussion Starter · #4 ·
I was also wondering if the rear end off a Durango R/T would fit a Gen1 Dakota?
 

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Well, running 500hp through the stock rearend might be asking for trouble... But I can't say for sure. Hopefully, someone with a "blown" Dakota/Durango R/T can help out on this one.

As far as runnning the Durango R/T rearend... That should be a good match. It's just the matters of width, axle mounting angle and shock location that'll be a challange. I've never compared them... With any luck they'll match up perfectly, but you'll have to do some comparing with a tape measure. Oh yea... don't forget that the bolt patterns are different.
 

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GenII Dakota
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409 Posts
Discussion Starter · #6 ·
Im still a little confused about the whole rear end thing.. would I have to worry about axle size too if I had more HP? Or is the differential about the only part that I really need to worry about... I just want something that can hold up... and I've decided to go with a 8 3/4 with 3.73... Help a confused kid out here haha

Thanks,
-Jason
 

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one again im goin to express my opinion
the 8 1/4 in your truck is the same 8 1/4 in many old school light mopars a bodies ect... it can handle plenty of power especially if built correct (good posi or spool if your putting down huge power, good axles and a stud girdle) 500 hp should be no prob for that rearend , but I would just get a good auburn gear posi unit (the same for any 8 1/4 w/ out the abs ring on the gear which yours is) and I wouldn't trust those axles passed 450 if the truck hooks hard. You can get custom axels made from just about anywear especially moser for reletivley cheap and you can change to 5 lug while your at it (all you would need is a set of 10 inch drums from an 89 dakota) hope this
helps

aftermarket axle 35% stronger
superioraxle.com can get them from summit $107 a piece i believe
6 lug p# pa5723
5 lug p# pa5768
info for custom made
length 30 3/4, holes 5 on 4.5 or 6 on 4.5 , 27 spline , both sides the same ,

FYI - there are numerous 8 1/4's running in the 10's and 9's , save your money and build what you got IMO hope it helps
 

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GenII Dakota
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409 Posts
Discussion Starter · #8 ·
So just a good Posi Unit and New Axles? ANd the 92 Dakotas are 8 1/4? I heard they were like 7 something... Yea, I really know nothing about rear ends so if anyone has anymore information or opinions, please post.

Thank you,
-Jason
 

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your is a v6 so most likely its an 8 1/4, you can tell by the differential cover, if it is round it is an 8 1/4, if it is an octagon it is a 7 1/4 and if it is a 7 1/4 junk that puppy and get your self somethin else
 

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GenII Dakota
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409 Posts
Discussion Starter · #10 ·
Streetdak, I know you did a V8 conversion and you just kept your same rear end setup didn't you? When you get the 360 put in, what do you plan?

So If I purchased the pa5768 axles and then a good posi unit with 3.73 gears, I should be alright.. correct?

About the 6 lug to 5 lug conversion... we happen to have a 89 dakota that we use as a work truck but would I be able to do a full swap and make the 89 a 6 lug and the 92 a 5 lug? I can't just steal the parts from the 89 because we use that truck :) Would I still have my ABS?

Sorry for all the questions I just dont want to mess something up and have my rear end yanked out from under me.. One more question.. when I do all this upgrading, is there anything else I should go ahead and replace/check?

Thank you,
-Jason
 

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GenII Dakota
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409 Posts
Discussion Starter · #11 ·
Ok, maybe I didn't make myself clear.. If I get the 6 lug axles and put a new differantial in there I should be alright and not need to worry about having a busted rear end, right? While in the process of this upgrade, are there any other corresponding parts I should check or upgrade.

Thank you,
-Jason
 
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