Can any one tell me right off hand wether a 10 bolt posi rear out of a 78 monte carlo will fit my 69 elky?

Direct fit - NO, Can it be done - YES

Are you talking about the complete rearend or just the posi unit? If your talking about the posi unit then...no, it will not fit. If your talking about the complete rearend then then yes, with some modifications. Here's the thing,..the overall width of the Monte Carlo rearend is shorter than the overall width of your 69 Elky rearend...your wheels will likely hit your inner wheel wells...therefore yes with some modification ...which might include tubing the rear of your 69...I say "which might include" because, no one I have ever heard of has ever done this swap...reason being the 7.5" rearend is much weaker than what the rearend in your Elky is, doesn't matter if it's a 10 bolt or 12 bolt in your 69...that one out of the Monte Carlo is waaaaaaay weaker. If it is just the posi, the parts are not interchangeable between the two rearends...no parts are the same internally between the two rearends because of the size difference. Rebuilding or getting a posi carrier for your 69 rearend is better in the long run...if that's what your looking to do.

There is a Powertrax Lock-Right locking differential listed as easy to install. It fits in where the spider gears usually are. It's made for sever driving conditions, which may mean off-road ??? Anyway , I haven't tried one. I see they are in the Summit catalog.
If you are into doing a gear change, there are several available posi units for around 500 bucks, for your rear end.

I can show you a couple of shelves full of broken Powertrax units. I went with an Eaton unit, IMO, the best around and rebuildable. If your rear hasn't been touched in a long time, figure on new axles and bearings while you are at it. Our axles don't use races for the bearings, so they end up wearing out.

When I did my rear, I went with an Eaton unit, all new bearings, new axles (Yukon) and new ring and pinion (US/Strange), with labor it was a total of $900.

Don't forget, if you just throw in a Powertrax unit and don't put everything back in exactly like it came out (spacers etc), you need to do a complete setup, consisting of checking backlash and tooth pattern checking.

That's good information. I don't have a posi in anything right now, but maybe later I'll go with one in my Ford 9.

im new to this, but i just had a question:
I have an 84 Elky and i had an accident which i had to replace the entire rear end.I replaced it with a rear end from an 81 el camino. What rear end gearz does it have? and what is the cheapest way to get both wheels to spin?

What rear end gearz does it have? and what is the cheapest way to get both wheels to spin?

pull the cover,and count the teeth on the gears,divide the big number by the little number...

the cheapest way is almost never the best way.
weld the spidergears (never try this at home with out adult supervision telling you not to)
a mini spool (not for the street)100$
a bolt in locker (read this post again)400$ i did not know that,thanks >> MM.
get a posi carrier and some new gears.600-1000$ :texas:

best thing to do is go to a junk yard and get another car around the same year (Chevelle) and take the rear out of that.:nanawrench:

pull the cover,and count the teeth on the gears,divide the big number by the little number...


That information can be found here → http://elcaminocentral.com/showthread.php?t=27935
and you can find the numbers / ID located on the front of the Passenger side Axle Tube about 4 or so inches from the carrier. You'll most likely have to clean the crud off to see them, their stamped into the tube. :dontknow: Also keep in mind, that will only be correct if the Ring and Pinion have not already been changed at some point in time.