# '69 GTO - Want to put in Posi & 4 Speed - Questions



## Lfryklu (Sep 9, 2013)

Hello,

New to the forum. I have a '69 GTO, and right now, it is literally a basket case, and it does not have an anywhere near correct rear end in it.

I want to put in a Posi unit and am going to 'start my hunt' with feedback from you guys.

I see something about 'Early' A Body Posi Rear ends ? 

Guess I did not know there was an Early or a Late, unless they are referring to '68 - '72 as being Late ?

Is that right ? I am guessing that it has to be '68 to '72 for 'bolt on' fit for my '69 ?

Also, for a '69 GTO, does it matter which would be more 'Correct' ? a 10", or 12" Bolt unit ?

How about gears ? Recommendations here ? Think I had a 3:73 my last '69 ...? Is that possible ?

I have a WT block with #48 Ram Air heads in this car. Also, I am looking for a Muncie M21 Close ratio 4 speed, I think this is the specified original for this car ?

Trying to go 'Original, but friends are suggesting a BW T10, and/or a Muncie M22 

Any feedback, or suggestions would be appreciated.

Thx - Lfryklu


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## ALKYGTO (Mar 29, 2010)

Okay Lfryklu, lets start off with you goals, originality, pro touring, race, cruiser, what are you going to do with the car primarily, show it, or drive it?

3:73's and no overdrive are going to suck (gas) and rev fairly high on the freeway if you want to keep up with traffic.

What do you have now? To me if you are going to change over to a stick and want steep gears in the rear consider a 5 speed. Some 5 speeds offer lower gearsets and a 1 to 1 5th gear so you can run highway gears in the rear also.

I guess we'll need some more info here. :seeya


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## Taxangler (Sep 10, 2013)

I had a Ford 9" installed with a 3.89 gear. They are pretty bullet proof rears. I also have a 5 speed transmission. The overdrive makes highway driving palatable. I am actually in the process of installing a Tremec TKO 600 with a .64 OD. I should have it installed to make the Wildwood, NJ Boardwalk show next weekend.


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## Lfryklu (Sep 9, 2013)

Thanks - I'm sure it is a good RE, but I really want to stay GM.

Yep, OD really helps with some RE to keep the RPM's down

Sounds cool though.

Best - Lfryklu


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## Lfryklu (Sep 9, 2013)

Thanks

Trying to keep with Muncie M21 Close ratio 4 speed - stock application.

4 Speed car with WT Block = 4 Speed motor

I know 3:73 is not good for highway cruising, but imagine most will be on the street, < 30 mph.

I found out the 12 bolt rear ends are only stock to '70, so that gives me what I need to know about 'correctness'... A 10 bolt is what I am now focusing on

Appreciate your response to help me 'narrow it down'...

Best - Lfryklu


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## ALKYGTO (Mar 29, 2010)

So.....you are going to cruise around at 30 mph primarily huh? I doubt that, seriously I think you'd be happy with a 3.08 or 3.23 gear. Pontiac motor makes enough torque that with the 3.73 or lower you wouldn't even need to use 1st gear.

Standard rear for WT 4spd was 3.55 I believe and that was with a pretty short tire which if you go with that and a little taller tire would be fine for highway driving too.


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## Rukee (Feb 8, 2007)

I have the 3.55's with the 4-speed and no issues at all going down the interstate.....except for the gas millage anyway.
Swapped out the 3.90's that was in the car when I bought it and the difference was night and day, with those I wouldn't even leave town.


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## chuckha62 (Apr 5, 2010)

Keep in mind that a BOP (Buick, Olds, Pontiac) 10 bolt is an 8.2" not an 8.5" like the ten bolt Chevy. Chevy also made an 8.2" but it is a "C" clip rear and not as strong as the BOP 8.2", which does not use "C" clips to retain the axles.


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