Thinking of swapping my original rear end 3.36 non posi for a 1975 3.55 posi any pros or cons with this set up? car is a base 327/250 hp. would this be a direct swap or are any modifications required?
1964 2 speed power glide 3.36 non posi carrier
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Re: 1964 2 speed power glide 3.36 non posi carrier
The 1964 differential uses a 1310 series u-joint flange; the 1975 uses a 1330 series u-joint flange. You would have to change the pinion flange on the 1975 differential unit OR you could use a conversion u-joint. You cannot transfer the 1964 pinion flange to the 1975 unit because the spline count is different.
The conversion u-joint is probably the easiest thing to do.
The only other thing you may have to do is to change the speedometer driven gear.In Appreciation of John Hinckley- Top
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Re: 1964 2 speed power glide 3.36 non posi carrier
As Joe mentions the 63-4 diffs used a 17 spline pinion so you will need a 1310 yoke for the '75. Your open diff is actually stronger then a 63-64 posi. The pinions were weak as well.
Now if you have a stock, untouched 75 diff you should really check it before installing it. I would rebuild it. There is not going to be much difference between the 336 & 355's. If you want want more launch go with a new set of Toms 373's.
General information on 73-79 differentials
1- soft faced axles- if original you have to check them and either replace or have them hardened if still good.
2- posi clutches- these use what I call "snowflakes" a term which seems to have caught on over the years. They are not too good.
3- Housing and posi case- good units but the cases have to be checked for cracks
4- 10-17 x 17 spiders- very good gears and the best of the 63-79 run.
I wrote this thread 11 years ago, it will help you.
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Re: 1964 2 speed power glide 3.36 non posi carrier
Thanks for the quick response conversion u-joint readily available?- Top
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Re: 1964 2 speed power glide 3.36 non posi carrier
Yes. NAPA #UJ353 is one that's readily available. I'm sure there are other brands. There must be a Dana-Spicer equivalent but I do not have the part number.
If it were me, I would replace both the forward u-joint with a standard u-joint and replace the rear with the conversion u-joint. Then, with the u-joints installed, I would have the driveshaft precision-balanced at a driveline shop.In Appreciation of John Hinckley- Top
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Re: 1964 2 speed power glide 3.36 non posi carrier
William
Why are you considering this project? As stated you are not going to notice much difference and with a 250hp I don't see the need for a posi. Seems like a lot of work and money for very little results. Just sayin !- Top
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Re: 1964 2 speed power glide 3.36 non posi carrier
Mine is making an occasional funny sound and probable needs to be rebuilt, think rebuild or possible change- Top
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