# rear end



## Chris-Austria (Dec 23, 2010)

Hi!

Can someone tell me what rear end I own? I couldn't find the codes on the axle where they should be on my 66 GTO. The numbers I found are:



















If I google the numbers I find some information that it is a non posi (xh) and someone else says that it's a posi from 1969. 
I want to know what year and how "good" this rear end is. (size, quality, max hp, posi, gear ratio..)
I know that my gear ratio is 3.55:1 because I performed a test.

Thank you very much!
Chris


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## Chris-Austria (Dec 23, 2010)

How can I tell if it's a 8.2 or 8.5 ten bolt?
Maybe it's a HD Safe T Track from 69.. but does this indicate a 8.2 or 8.5?
Also can you tell if I have a clutch disc type or cone type differential by these numbers? (which one is "better"?)


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## 68GTO4004Spd (Jun 19, 2008)

That is a 1969 Tempest(GTO) HD Safe-T-Track 4 pinion 8.2 in with cone clutches. Usually good up to around 400 hp if you not railing on it constantly. When I replaced my rear end, I got that same one in a 68 code ZH. If it has an "N" on top of the pumpkin near the front, then it is a nodular, which means it has a stronger steel alloy than the normal rear end.


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## Chris-Austria (Dec 23, 2010)

Thank you, very interesting!
I'll search for the "N".. If it supports 400hp it seems to match my engine. Is it possible to upgrade the rear end to support more hp? New posi unit or gears? (for a reasonable price..)
What makes this rear end "HD"? What's the difference to a non-HD?


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## 68GTO4004Spd (Jun 19, 2008)

HD is 4 pinion as compared to 2 pinion on a stadard rear end. That is probably the strongest 8.2 rear end made. The only way to get a stronger rear end is to get a 12 bolt or a Ford 9" or Moser. If I were you, I would run the piss out of it and if you happen to break it, then go to a stronger type. I doubt if you will ever hurt it unless it is extremely worn out. I'm sure there a plenty of people on here that would kill for the one you allready have.


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## ALKYGTO (Mar 29, 2010)

:agree That's a good one Chris. Wish I would have never sold the original out of my car. It was identical to what you have .


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## Chris-Austria (Dec 23, 2010)

I don't go easy on the rear end.. but since the differential of a friend broke I was wondering if I should be more careful with mine. (she has got a GM 7.5 and the cone clutch broke.. they repaired it, I'm curious if the welded clutch will be durable)
I'm happy to hear that my rear end isn't the weak link since I have some more hp and maybe I'll add a roller cam and some other things in the future.
Thank you for the good news


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