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Old June 3rd, 2016, 12:52 AM
Chuck78 Chuck78 is offline
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Default Re: 5 speed/o.d. swap - A833 MY6 "NP440" 4 speed o.d.

Well... the. TKO-500 Tremec transmission ($2450+ $350 more for truck shifter locations) would be the top choice if I had a much larger budget, but after all this consideration, I have done more researching...

The A833 rpo code MY6 "NP440" 2 wheel drive 82-86 c10 chevy truck transmission (& rare 82-89 g10 4 speed vans) would be the perfect swap for me with a Saginaw in place currently, as it would bolt right up!


Note how one shift fork/linkage bracket us upside down from the other. For ease of redesign reasons, when they took the a833 4 speed and converted it to an o.d., they made o.d. the 3rd gear position, with 1:1 still as 4th. They did this to keep the arrangement similar with minimal changes, knowing that they could just reverse the shift linkage and have the shifter hit Overdrive 3rd gear in the standard 4th gear shifter position, and then the 1:1 4th gear would be shifted into in the standard 3rd gear shifter position.


These trannies are incredibly strong. The only downfall is the cases wear at a point where the end of a shaft rides in a register in the case, they get egg shaped. The cases can be machined and a steel bushing pressed in place to repair this.
Another downfall I've read (but not as common) is of the needle bearing wear on the input shafts, primarily blamed for GM's poor recommendation of Dexron III - mercron automatic transmission fluid vs a good gear oil (some say 50W gives much better shifts)
Lastly, for our GMC V6's, we need the more rare version of these. Most came with a GM bellhousing to block pattern, but a special bellhousing that adapted to the odd looking Chrysler pattern on most of these transmissions. Some of them were made with the standard gm transmission pattern, but more than not had the Chrysler pattern with the gm engine adapter bell.
Chrysler bolt pattern version requiring it's exclusive GM SBC pattern bellhousing:


These things are getting harder to find. Some have aluminum cases, some have steel cases. I am not sure of the correlation between 2wd & 4x4, aluminum vs steel, in terms of the likelihood of finding the gm trans pattern that we need to bolt to our gmc v6 bellhousings.

Last edited by Chuck78; June 3rd, 2016 at 05:34 AM.
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