Should I go POSI???

[JBswth]

The truck is an 85 K1500/LB/REG CAB/350/400/208/6"/35's. Still has an OEM 3.08 open diff 10 bolt. Looking to re-gear and am questioning if I should just spend the extra money and put limited slip in while I'm at it. I actually have done very little driving of this truck as its an in process project so I have zero road use to go from. I think I will go with 3.73 or 4.11. Just would rather not have a 1 wheel peel machine in wet or loose traction environments if these are prone to do that.

Can anyone provide real world experience with different set ups related to my question. I have done a ton of online research and most everything I find is speculative and calculated rather than real world drivability.

I wont do any towing and it wont be a daily driver. Mainly a going to town truck and hopefully some shows if I can get it spruced up well enough. I guess that could mean some highway but limited at best.

Thanks

I wouldn't bother spending the extra money. Just go with 4.11 or 4.56 gears. Posi is good if you have to use dirt roads in the winter, that become mud roads. It can help you avoid getting stuck so easily.

J. B.

 

[Zelph]

You say that you have a K series truck. If money is an issue, I would advise skipping a rear locking device and spending that money to have the front gears done as well.
Having both front and rear drive is superior to just a locked/posi rear drive.

 

[Craig Nedrow]

I used a Yukon Lunchbox locker, and like it. Mine was a FF14 10.5 open diff, so easy to change out and done in a day. However I live in the hills in central Commie Wa St. and my driveway can be a challenge in the winter, yeah we get a fair amount of snow up here. I do have a write up on the swap, will find it if you were interested. I also did the same to the front end, so quadra-track. Having said that, it is a handful in 4 wheel drive on the road, but awesome on the ranch in the hills. I am converting to a twin stick, but haven't got it completed, but others here loved it, hence the reason I am converting. Cost around 250 bucks. BTY motor was a 454 cam, intake, exhaust, gestimate HP 375hp, MANY burnouts, and rear end perfect, trans, not so much, got a write up on that to.

 

[78C10BigTen]

I used a Yukon Lunchbox locker, and like it. Mine was a FF14 10.5 open diff, so easy to change out and done in a day. However I live in the hills in central Commie Wa St. and my driveway can be a challenge in the winter, yeah we get a fair amount of snow up here. I do have a write up on the swap, will find it if you were interested. I also did the same to the front end, so quadra-track. Having said that, it is a handful in 4 wheel drive on the road, but awesome on the ranch in the hills. I am converting to a twin stick, but haven't got it completed, but others here loved it, hence the reason I am converting. Cost around 250 bucks. BTY motor was a 454 cam, intake, exhaust, gestimate HP 375hp, MANY burnouts, and rear end perfect, trans, not so much, got a write up on that to.

Leaves nice 11s!

 

[Craig Nedrow]

I have lots in the 12.5 version as well, poor TA are toast. you can here a chunk of tire come loose when I shift from second to third.

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[Grit dog]

You do understand that 2 wheel peel in wet or slick conditions gets you sideways, backwards or off in the ditch right?

Huh?

 

[Grit dog]

I wouldn't bother spending the extra money. Just go with 4.11 or 4.56 gears. Posi is good if you have to use dirt roads in the winter, that become mud roads. It can help you avoid getting stuck so easily.

J. B.

I guess he did say not much highway use…as 4.56 would be miserable on the highways. 4.10s are bad enough with 35s and no OD.

 

[Ricko1966]

Huh?

A lot of people don't realize that one wheel peel vehicles in rain,snow etc. spin 1 tire and continue in the direction you are steering. He was concerned about one wheel peel in slick conditions. I asked if he knew if both wheels break loose you go sideways or off in the Ditch or spin out. Not a problem for some people,but others don't realize posi has pros and cons. Drift cars aren't running open diffs,too hard to get them sideways they run posi or spool so they can get them sideways.Manufacturers now have stability,traction control and ABS because not everybody knows all the in' and outs of posi,brake modulation,etc.

OMG @Grit dog , if you hadn't made me start thinking. My 69 GTO when I was 17, I loaned it to buddy to take a girl home frome a party.He didn't come back for hours!!! He got into a race, with my car, he didn't have the skills, it got sideways he ended up hitting a phone pole,bent my frame,broke a motor mount I had forgotten all about that you SOB!

 

[xm20k]

Oh, yah too much gas in a turn even when it's dry hell even in a straight line it can get loose add wet and it can get out of hand in a hurry. A posi unit is not as bad as a spool because it at least will differentiate when you back out of the gas, a spool will fight you thru a turn gas or not. My first ever accident was due to playing too much and a posi driving me into a 180 while going downhill. A lot of people get in a car that makes decent power and a posi and get in trouble what do you think all the Mustang vs crowd videos are caused by.

 

[J-SQUARED]

You say that you have a K series truck. If money is an issue, I would advise skipping a rear locking device and spending that money to have the front gears done as well.
Having both front and rear drive is superior to just a locked/posi rear drive.

Doesn't currently have the front shaft in. Planning on re gearing the front the same and rebuilding all of the bearings and seals in the hubs/spindles.

 

[Dleslie212]

I like the eaton tru trac limited slip...

I'll echo above that 6in and 35s with a 10 bolt is a tall order. 2-4in and 33s is about the max I'd consider and i would regear to 3:73 or 4:10 in that scenario.

Second vote for the Eaton tru trac. Installed on my 12 bolt with 3.73 and 33" tires. Just dont try to gas it real heavy when cornering