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Does anyone know where someone might find a Spicer 5831 Auxiliary gear box. I need a 5831 or the 5831A with the .73 overdrive. I am not having any luck and very few know what it is. I desperately need one for my project to couple behind a Allison transmission on a old Mack, which I am turning into a giant pickup Truck. And does anyone know how much someone should pay for one of these. I have heard numbers all over the place?. Any help would be greatly appreciated.

Thanks Don

To start your search put a wanted ad in the swap meet section here, (not the general forum)

If you're trying to figure out exactly where to find one then good luck. I don't know of any one make or model of truck that always had one, they were options and you just have to search junk yards and see where and in what they turn up.

Spicer also made larger auxiliary transmissions which may or may not be better for your application, how much HP and weight are you dealing with?

I have owned a 5831 that I bought cheap and sold for I think $250, it needed a rebuild and had no "extras". finding one with factory mounting cross members, shifter, and some drive shafts to work with can cost more and be well worth the money compared to fabrication and scrounging that stuff later.

Keep asking around and keep your eyes open, you ought to eventually find what you want for more like a few hundred $ and not a few thousand.

$600.00 to $1200.00 depending on condition and what extras will come with it.

But be careful Horse Power is an issue with these older aux boxes.

Most were not designed for more than 200HP at the flywheel.

Does anyone think that a Mack 300 Engine is to much for the Spicer 5831 Auxiliary transmission. The Engine tag reads 285hp. This Truck will never pull anything heavier that a Car trailer.

Don't forget that the "brownie" boxes were behind the main transmission so they were receiving engine torque that was multiplied by the lower gear ratios in the main transmission. I think you should be fine given the expected loads you will be pulling.

SimS

Brownie boxes were designated(sized) based on the engine torque, thus a 5000 series was designed to go behind a 500 ft. Lb. engine. I think that a 6000 or 7000 series Brownie would be appropriate for your application. It also depends to some extent on the GVW of the vehicle.

In general, 6000 and 7000 series boxes are more plentiful because many people want one for a pickup, of course they weigh slightly more, but a few hundred pounds doesn't much difference in a truck.

If your truck doesn't have a parking brake, look for a Brownie with an attached brake.