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5 speed or 6 speed for D150.
https://www.slantsix.org/forum/viewtopic.php?t=63588
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Author:  sixinthehead [ Fri May 10, 2019 4:16 am ]
Post subject:  Re: 5 speed or 6 speed for D150.

The 8 3/4 is a different design (Hotchkiss) where the axle housing doesn't use a rear cover at all - there are no bolts visible from the rear of the differential.
Instead, there is a ring of studs/nuts facing forward toward the driveshaft.
Once the axles are removed from the housing, the whole differential/carrier/center section comes out the front in one 'chunk'.
Then you simply exchange it for a different one with the gears already set up.
The whole gear swap can be done in less than an hour.
Don't forget to change the speedometer pinion to match whatever gear you choose.

The 8 3/4 housings were more commonly found in cars and come in various widths.
You should be able to find one with a similar overall width, though you may have to move the spring perches.
They usually have the 5x4.5" bolt circle, which should match your '82 truck.

You also might be able to find a different 9 1/4 rear with the desired ratio and swap the whole thing.
That kind of swap is also not bad - you are basically dealing with brake bleeding and e-brake cables instead of gaskets and gear lube.

Author:  enrique lopez [ Fri May 10, 2019 3:06 pm ]
Post subject:  Re: 5 speed or 6 speed for D150.

swapping a 9 1/4 sounds as an easier option.

thank you for all your input, I have some thinking and searching to do.

Author:  sixinthehead [ Fri May 10, 2019 3:17 pm ]
Post subject:  Re: 5 speed or 6 speed for D150.

For what it's worth, 1/2 ton V8 2wd automatic trucks are more likely to have highway gears.

Finally, one other easy option: taller tires.

Keep us posted :wink:

Author:  Montana A Body [ Fri May 10, 2019 5:39 pm ]
Post subject:  Re: 5 speed or 6 speed for D150.

I have a gear vendor overdrive behind a nv4500 and a 12valve Cummins. I have not lost fifth gear or torn up my transmission towing with this package but there is a lot of maintenance with the gear vendor and I do believe that it will be giving out soon enough due to all the shavings on the magnet each time I service it. Which is every 5000 miles.

If I had a five speed that would hold up to towing I would much prefer that over the gear vendor.

I probably have a hundred thousand miles on the gear vendor and this rebuilt transmission. All previous rebuilds only lasted fifty thousand or so. I now only towe in fourth and overdrive on the gear vendor.

Author:  Montana A Body [ Tue May 14, 2019 12:36 pm ]
Post subject:  Re: 5 speed or 6 speed for D150.

Talked to gear vendor today about shavings on the magnet and color of fluid. The man was not overly concerned and basically said it was normal wear. Told me some folks get 300000 miles on the gear vendor and mentioned some indications of the gv getting weak which mine does not have. Hoping I get another 100,000 or so out of it!

I guess I can use the same unit behind my 904 someday if I ever so choose also. With some component changes.

Author:  enrique lopez [ Thu May 16, 2019 2:52 pm ]
Post subject:  Re: 5 speed or 6 speed for D150.

thank you for all this input, I highly appreciate it.

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