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RAVEN
07-21-2001, 08:51 PM
o.k., so i have a '67 108 1/2 ton (as evidenced by the 5-bolt wheels), with a 283 and 350tranny, and i want to put in a posi rearend.

I've seen ads for earlies without posi's as original equipment, and they all seem to use 12-bolt rearend posi's, the thing is, my rearend appears to be a 10-bolt by counting the # of bolts on the bellhousing for the rear axel. Am I couting the bolts in the right place?

I assume then to do a swap without replacing the whole rearend, I need a 10-bolt posi unit like out of a nova or something.

Is this right?

will that fit in the original housing or do I (well, the shop I have it done at) need to do something different?

I can pick up either a 12-bolt or 10-bolt posi unit and gears used from a local trade rag, but I want to get the right one.

Also, the 10-bolt seems to come in two sizes from reading hot-rod mags, either a 8" or a 8.5", and an "old" or "new" GM style. ?????????

if the 10-bolt is what I need, which of these is it?

thanks in advance of answers (err, maybe that's not so wise... well, too late! http://www.vcvc.org/ubb/wink.gif )



[This message has been edited by RAVEN (edited July 21, 2001).]

ahighdiver
07-21-2001, 09:39 PM
The rear ends in the vans are dedicated width. You have to use the same axles. The ten bolts you counted on the rear end cover are correct. the ten bolt is a Salisbury limited slip. There are no gears for that housing that will make it a posi. You will have to find a full floating twelve bolt.
Some one here can discribe it to you. But it will have to come out of another van.

RAVEN
07-21-2001, 09:56 PM
by "full-floating" I take it you mean I need to swap out the entire rear-end and not just the differential dealy...

*sigh*

damn! its never easy is it?

http://www.vcvc.org/ubb/wink.gif

[This message has been edited by RAVEN (edited July 21, 2001).]

tonye66
07-21-2001, 10:00 PM
Hey,
I have been lucky enough to get a van with posi. I know that you counted the right bolts. I found one that I am using in my new car from the junkyard. You will be surprised at the amount of cars in the junkyard that have posi's still in them. Depending on where you live, most junkyards have posi cars in them. I do believe that you have an 8.5" ring gear in your van. You must get an 8.5" 10 bolt for your van unless you get a new center section. I can look at the local junkyards for you if you want and I can buy you one. You can send me the money and I will send it to you.

Tony

RAVEN
07-21-2001, 10:19 PM
well, I'm sure I can find one if I know what to look for, and in fact there's a couple of posi rear-ends forsale in a swap 'n sell mag locally (ALREADY PULLED!), both 12-bolt and 10, some the whole rearends and others just the posi carrier and pinion gears....

I was hoping to make the swap as "painless" as possible, keeping my original brakes and axels and just replacing the center (well, actually I hoped I could get the gears 'n posi and stuff it in the original housing, but ahighdiver dashed those hopes--thanks SOOOOO much!!!! no really! http://www.vcvc.org/ubb/wink.gif )...

if I'm gonna have to get rid of original 10-bolt (just the center or the whole deal? it might actually be easier to swap the whole deal if i can find something) anyway, wouldn't a 12-bolt posi be BEEFIER/better?

I'm gonna be doing some towing with the beast, so beffier is better if its not too hard to find/put in, and if in fact the 12 bolt IS beefier than the 10...

thanks




[This message has been edited by RAVEN (edited July 21, 2001).]

tonye66
07-21-2001, 11:17 PM
I forgot to mention that if the splines on the axles have to match. You would have to count that before you could even look for a ten bolt anything. If you do get one that matches, grab EVERYTHING in the center cection. It will be much harder to install without all the parts. I personally think that open rear ends are fine if kept up and not abused. You could have the spider gears welded to have a locked rear. The only problem with that is that the tires would squeal on a turn. I think that is a good plan on a low budget.

Tony

Yeggster
07-22-2001, 11:21 PM
Posi's are available for almost all diferenials.....there are so many diferent kinds though.....check out a 4X4 mechanic in your area......they can tell in a few miutes if it's worth setting up you existing rear end with a posi.

I needed a heavy rear end in my 66 because I carry/tow so much stuff all the time.

I put a huge 14 bolt rear end out of a mid 70's 1 ton pickup........I rebiult it and installed a Detroit Locker no-spin.......works great.......it's just an inch or so wider on each side than the old width

bearing that in mind if oyu are up to the chalenge of a full rear end swap any GM pickup would do for a doner.

You have to grind off and reweld the spring mounts (they are mounted much farther apart on the earlys) and redo the drive shaft (or maybe just the back U joint) to match.

Not too bad of a swap really

Yeggster

RAVEN
07-27-2001, 08:23 PM
I'm planning on abusing my rear-end, (now, now, I didn't mean THAT one you sickies! http://www.vcvc.org/ubb/wink.gif ), so I think I will want a posi eventually, if only to get the tires to grip better when peeling out...

so I CAN get a posi to fit in the current housing if i get the matching spline #s and everything else, or are we talking about cutting out the "center" and welding in new housing to fit new gears?

yegg, did you change the whole rearend or just the "center" section, cutting and welding the diffential housing to the axel housing of the stock rearend?

just wondering if the extra inch on each side is for the center housing or if your tires are sticking out from a wider whole rearend... I'm running rather fat tires currently, and so am already sticking out a fair amount with the stock rearend...

I know hot-rodders shorten axels and tubb reares to install fat tires and hearty posi gears, but I was hoping for something a bit more simple (for now.. *start forboding music*)




[This message has been edited by RAVEN (edited July 27, 2001).]

tonye66
07-28-2001, 12:29 AM
Generally all GM 10 bolt 8.5" rearends are identical. I have a friend who put an 8.5" 10 bolt posi in a 71 Grand Prix which he got from a 68 Chevy Caprice. Now-a-days the posis are not quite the same as they were years back. Try to get one from a pre-1980 GM car. The open rear end is usually only bad when you are stuck in mud or snow. The posi in my van is original and it does move in snow unless the pumpkin straddles a patch of high, frozen snow in the middle of the alley. I can't remember the term for that, it might be bottoming out (not sure).

Tony

alan77520
07-28-2001, 03:06 PM
It is called "high centering"

Alan

<BLOCKQUOTE>quote:</font><HR>Originally posted by tonye66:
Generally all GM 10 bolt 8.5" rearends are identical. I have a friend who put an 8.5" 10 bolt posi in a 71 Grand Prix which he got from a 68 Chevy Caprice. Now-a-days the posis are not quite the same as they were years back. Try to get one from a pre-1980 GM car. The open rear end is usually only bad when you are stuck in mud or snow. The posi in my van is original and it does move in snow unless the pumpkin straddles a patch of high, frozen snow in the middle of the alley. I can't remember the term for that, it might be bottoming out (not sure).

Tony<HR></BLOCKQUOTE>

tonye66
07-28-2001, 08:29 PM
Thank You!

Yeggster
07-29-2001, 11:46 AM
I always though "high Centering" was when the vehicle got stuck on a hump because it was to long.

Yeggster

alan77520
07-29-2001, 11:56 AM
It also works if it is too narrow.

Alan

<BLOCKQUOTE>quote:</font><HR>Originally posted by Yeggster:
I always though "high Centering" was when the vehicle got stuck on a hump because it was to long.

Yeggster<HR></BLOCKQUOTE>