# All Points Bulletin For '66 Gto Rear End Questions



## take5 (Aug 9, 2009)

Question #1. What quantity and type of gear oil goes in the rear end axle for '66 GTO - I am replacing the rear seals and will need to refill.

Question #2. For rear brake drums on '66 GTO what is the minimun to have for turning rear drums. GTOGUY passed this information along about 2 weeks ago on a different subject being discussed and would appreciate because I'm not certain what topic it was tied to.

Thanks for keeping this restoration moving along.
My '66 GTO has been on jack stands for the last 4 months first completely rebuilding the front end & now getting a handle on the rear end.


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## geeteeohguy (Feb 2, 2008)

If it's a limited slip (safe-t-track) diff, you'll need limited slip gear oil or you'll need a bottle of the special limited slip additive. Napa has both...I used their limited slip 75-90weight with the additive as well. You'll need 2 quarts, but won't quite use it all. Fill until it comes out the filler plug hole. Originally, 90wt GL3 gear oil was called for, but straight 90wt is no longer available. You'll be fine with the 75-90 or 85-90 GL3 or GL4. Brake drums: don't cut them unless bell mouthed, grooved, or out of round. Take shallow cuts until it just cleans up. go easy. Maximum diameter is 9.560". Standard (new drum) dia. is 9.500. That gives you just .060" to play with during the life of the drum. Good luck.


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## take5 (Aug 9, 2009)

Thanks Geeteeohguy.
I found this GTO Forum after my car was in the shop & I will have picture of car down the road.


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