How can I tell if I have a real W27 rear or just an after market cover?

 

Well the center section is aluminum, so perhaps see if a weak magnet will stick to the main housing

 

Also on the right rear inboard side of the axle housing tube there are two letters stamped in and are about 1/4" tall.
Should read
SV for the 3.23:1
SX for the 3.42:1
SZ for the 3.91:1
This is a '70 only option for the complete W-27 rear end and '71 was the cover only. As for the covers, there are subtle ways to tell if aftermarket.

 

If it falls off your car just increased in value by about 8-10,000

 

OK. I'll bite.


What are the subtle ways you can tell if the cover is an aftermarket and not an original GM issue from back in the day?

 

The price?

:-)

answers both questions...

 

The difference in price never seems subtle to me.


How can you tell by LOOKING AT IT, OKAY?

 

OKAY
I think... the reproduction cover has no GM Part Number in it whereas the GM part does? It's quite small, like 1/8" characters, and down in amongst the ribbage.


AHA

look at about 2:00 position on this which I found by, you know, googling pertinent words:


http://s685.photobucket.com/user/jms...M2065.jpg.html

HPIM2065.jpg

Or, not... this Parts Place ad shows the PN in place on what is presumably the reproduction

http://www.ebay.com/itm/1964-72-Olds...-/350558386577

So, look for minor details like the crispness of the casting characters. The Google search brings up numerous images, one can probably find a few differences upon close examination.

 

I thought t he original poster was talking about the whole differential? Not just The cover

 

Posts 1 & 2 covered the center section pretty well


Post #5 then delves into the cover alone which in the other thread referenced appears to be well defined. Machined surfaces and crispness of lines.

 

 

Mine is a '72 factory 442, so if only a '70 option mine wouldn't have come with a true W27 anyway? I will check for the code you mentioned as well. I haven't got a magnet handy. My car originally had a 350 and has a 455 now, so I am wondering how far somebody who owned the car before me went. The cover could be show only. Thanks.

 

With the supplemental info you've provided, I'm gonna go ahead and guess that yours is a reproduction cover ...


Nice looking car, regardless.

 

You might want to keep quiet about not having a magnet handy, lest you lose your Man License.

How tough can it be to round up A MAGNET?

 

Oh yeah that's right. You and I spoke a few years back about the front end and that this was Col Wickham's (RIP) car. Searching his threads briefly did not reveal the source of the W-27 cover but I did see where he bought the car off a guy in Lexington NC.

As far as the differences in the covers, there have been several threads covering this and joesw31 nailed it in that thread.

Another thing to consider is the "original" mold(s) that created the factory ones would've been also used for the ones bought over the counter at the dealership but not necessarily the ones used for producing the re-pops from other vendors.

Also touched upon before was the use of black bolts as opposed to "bare" bolts.