8 3/4 question

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dropshot1

dropshot1

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Can anyone tell me if it would be cheaper to buy and have installed a 3:91 ring and pinion and a sure grip in my 721 case or buy the pumpkin already assembled
 
dropshot1 said:
Can anyone tell me if it would be cheaper to buy and have installed a 3:91 ring and pinion and a sure grip in my 721 case or buy the pumpkin already assembled
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It's probably cheaper to have gears installed in your case.
 
Finding an operational unit should be cheaper depending on condition.
Plus, you can always switch out units back and forth.
 
mycuda said:
Finding an operational unit should be cheaper depending on condition.
Plus, you can always switch out units back and forth.
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Like dropshot1, I too am looking at the price point of each option. I'm going with something in the 3.91 range for my 742, but like the current 3.23's for cruising on the highway and longer trips. I think picking up a chunk and swapping it would be ideal. But I have no idea how to actually swap them LOL! Is it as simple as taking a set-up 3.91 chunk, pulling the axles, pulling the 3.23 chunk and sticking in the 3.91? And special adjusting/tools etc?

Thanks as always!
Pat
 
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Divenut said:
Like dropshot1, I too am looking at the price point of each option. I'm going with something in the 3.91 range, but like the current 3.23's for cruising on the highway and longer trips. I think picking up a chunk and swapping it would be ideal. But I have no idea how to actually swap them LOL! Is is as simple as taking a set-up 3.91 chunk, pulling the axles, pulling the 3.23 chunk and sticking in the 3.91? And special adjusting/tools etc?

Thanks as always!
Pat
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being a 741 case, you can find those pretty easily and for cheap. I'd just buy one with the 3.91s in it and then simply swamp the pumpkins in and out when you want to go cruising, no special skills or tools needed, especially if you go nonadjustable bearings on your axles..
 
741 is the weakest of the units..489 and 742 are stronger I personally like buying them done have bought a few from Randy's always happy with them,I believe DR. Diff has the best price..
 
Everyone always says 741s are weak but they are plenty strong for most street able muscle cars.
 
dukeboy_318 said:
being a 741 case, you can find those pretty easily and for cheap. I'd just buy one with the 3.91s in it and then simply swamp the pumpkins in and out when you want to go cruising, no special skills or tools needed, especially if you go nonadjustable bearings on your axles..
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I have a 742 in the Duster and think I'll got that route, i.e. find a chunk, get the 3.91's set up. Then find a local FABO member to help me swap it that first time :)
 
Divenut said:
I have a 742 in the Duster and think I'll got that route, i.e. find a chunk, get the 3.91's set up. Then find a local FABO member to help me swap it that first time :)
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742s go for a tad more money but never the less, much easier
 
Unbolt driveshaft and axles. Slide axles out a bit
Divenut said:
I have a 742 in the Duster and think I'll got that route, i.e. find a chunk, get the 3.91's set up. Then find a local FABO member to help me swap it that first time :)
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Remember, you dont need to look for specific chunk if your gonna have 2 any way. Could find 741 conestyle suregrip cheaper pending gear ratio.
 
can you easily swap between the numbered chunks? ie can you easily swap a complete 489 on a car that has a complete 742 in it now? I am keeping my 742/3.91 but want a second chunk with something taller for the freeway like 742 or 489 with 3.23s in it.
 
Bob Wilkie said:
can you easily swap between the numbered chunks? ie can you easily swap a complete 489 on a car that has a complete 742 in it now? I am keeping my 742/3.91 but want a second chunk with something taller for the freeway like 742 or 489 with 3.23s in it.
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Yes but you'll need to find out which pinion yoke you have. The 489s are usually large yokes as where the 742s sometimes are but normally are small yoke. That said, they do sell u joint that will let you adapt to either yoke just fine fine. Other that that, it's a direct swap
 
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