Where can I find a factory posi rearend

[Gagecampbell82]

I have a 1982 c10 short bed with a 350/th350. I recently bought a s10 for my daily driver so now the c10 is becoming a toy.

I'm curious if anyone knows what I could find a factory posi rear end at. Or if need be a lower geared rear I can put a locker in. id prefer a 12 bolt but might consider a 10 bolt. Mine is a 10 bolt 2.73:1 open diff and it will burn 1 tire all day long. So I'm looking for a posi rear that will hopefully bolt up or need very little modification to work before I start moving weight around to help make it hook up (I know I will need to do this anyway most likley) but I would also like to keep a 5 lug rear wheel. Any advice would be greatly appreciated. Thanks in advance.

[roundhouse]

10 and 12 bolt are about the same strength

If you want strong you gotta run a ford nine inch


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[SkinnyG]

I ended up fully rebuilding mine and adding a truetrac.  I couldn't find a 12-bolt w/posi locally that didn't need a full rebuild anyway.  They haven't rolled off the assembly line since, what '81?

What about a lunchbox locker?  It would be the cheapest.

[Gagecampbell82]

I'm not to familiar with a lunchbox locker but my main concern is the 2.73 gear ratio. I've been told to swap to 3.73s or 4.10s all by different people. But the one thing they all have said in common is that the 2.73s were to high and that's where all my wheel spin is coming from. So should I find a set of gears out of another c10 10 bolt and buy a locker? Sorry I'm just not to familiar with rearends yet.

[VileZambonie]

Personally I hate lockers, I would go with a limited slip differential. The factory units are weak and not made for tire frying but if you don't intend to beat on it then look for a factory setup.

http://car-part.com/

[fitz]

But the one thing they all have said in common is that the 2.73s were to high and that's where all my wheel spin is coming from.

I think you got some bad advice.

[SkinnyG]

I had 3.07 gears in my 12-bolt.  Problem was a built a high-compression cam'd motor that needed more stall in the converter.  Which needed more gear since I ended up cruising below the converter stall speed and the cam's rpm range.  I went 3.73 gears and a Truetrac.

Truthfully, the general driving around isn't really much different.  Full throttle launch is much better.  And highway cruising with the TH350 is buzzy (close to 3000 at 60mph).  Fuel economy hasn't changed - probably because the cam is now operating efficiently at 3K rpm.

If you're getting lots of wheel spin with 2.73's, you're going to get even more with 3.73's or 4.11's.  You will WANT a posi with deeper gears.

The "lunchbox" locker replaces the guts of your open diff.  You can pull it out and sell it if you don't like it, and convert back to an open diff.  Advantage: no extra cost of gears and the install/setup.  If you are set on getting gears, get the posi that suits your useage.  Each type (Gov-Loc, clutch, cone, torsen, locker) have their strengths and weaknesses - pick the one that best suits you.

[Gagecampbell82]

So what would you guys suggest would be the best setup. It's a 2wd automatic that I really want to make into a truck I can drive on the street some and take to the drag strip. I just want to make it hook up and not smoke the tires (Or tire) when I stomp on it. I've always been told to buy a car for a hotrod because it's much easier to make hook up and get more weight over the rear. I don't know to much about  lockers and limited slip/posi and the advantages vs disadvantages. Where would you suggest I look to research this kind of stuff? Thanks again and sorry for the lack of knowledge.

[SkinnyG]

Just start Googling limited slip designs or something.  You could start here: https://en.wikipedia.org/wiki/Limited-slip_differential

Gov-Loc - OEM for truck, open until you need it, then it either locks or grenades.
Cone-style - OEM applications, not rebuildable "Auburn"
Clutch-style - probably the most popular
Helical-style - feels almost invisible, goes "open" if one wheel is off the ground - best, in my opinion, for daily drivers and fwd. "Torsen"
Ratchet-style - noisy and abrupt, super strong, great for dirt, drift, or drag - maybe not the best for a daily driver, but you could "live" with it as a toy "Detroit Locker"
Spool - Or the "Lincoln Locker", straight or sideways, not much in-between.

[Gagecampbell82]

Thanks this helped a lot. Based on what I've been researching into these and I believe I'm looking for something like a Detroit locker or maybe a trutrac. The noisy turns and ect of the Detroit won't bother me.  It won't be driven daily just on weekends and taken to the track. But would you suggest I stay with the 2.73 ratio or change it? Like I said it's a 2wd 350/th350 automatic. The engine has mostly only bolt ons right now (msd ignition, 4bbl edeobrock 600cfm, headers) and the trans has a 2500 stall converter and a b&m shift kit. I'm also running 275/60/15s if that matters. I plan to do alot more but I figured why build the engine until I know I could get it to the ground anyway.

[SkinnyG]

If you have a 2500 stall, you really need to be cruising above your stall speed.  With those tires (same as I'm running), that means 3.73:1 gears (which I'm running).  If this is a weekend/track-toy, consider 4.11 gears, but highway driving will be even more buzzy.  3.73's are close to 3000rpm at 60mph.

Then build the engine.  You could get a pretty rowdy camshaft for those 4.11 gears.  I have 231°@.050 with 108°LSA.  It's plenty snotty but very driveable - even more fun with the 3.73 gears.

Then get Cal-Trac bars if traction is a problem.  Or four-link it.

If you really intend to drag race it, I would recommend the Detroit Locker, no question.  If you plan on driving on icy roads in winter, probably not.

[Gagecampbell82]

Thank you. Now I have an idea what I'm going to be looking into starting next spring. The PO lowered the truck incorrectly (imo) by reducing the springs in the back to only 2 leafs and no overload leaf. Which is honestly where I believe most of the wheel spin is  coming from. And I'm not sure traction bars would clear  due to pot holes and ect. on the back roads where I live (north alabama) but I would like to 4-link it for sure. 

[Irish_Alley]

why a 2500 stall? stock is about 1500, most you should need with no big power mods is 1800ish. theres a reason why most trans now have od and its not to keep your cruising rpms high its to lower them. yes you want to be cruising above your stall speed to reduce the slip and trans temp but your problem might just be the 2500 stall or the tires or your right foot.

[Gagecampbell82]

The only reason I have the 2500 stall is because we pieced the truck together in our back yard about 2 years ago and my girlfriend's dad had a buddy with the tranny for sale with the stall. I got it freshly built for only $150. He built it for an older man to go behind a 400 small block in a corvette but he brought it back a week or 2 later and said it shifted to hard  for him so he paid him to build another tranny and let him keep that one for the labor swapping them. So I threw it in there with the tranny. But I did have a stock converter from a worn out longshaft th350 from the parts truck. I just didn't know any better.lol.

[Irish_Alley]

dont reuse a tc. if theres crap in it from the old trans it will just contaminate your good one. you can get a stock stall for $80 at the parts store. in my 86 c1500 i did the same thing. my trans blew up a buddy had one that was built but he took his truck off the road so he gave it to me. the stall wasnt 2.5k but around 2k. it shifted hard and you had to build up the rpms just to get moving. i ended u blowing up the rear (it was on its way out anyway) and im kind of glad cause i didnt have to drive that transmission anymore