Hot Rods Aux. Chelsea overdrive box

Does anyone here have any information about the Chelsea Overdrive gear box that is mounted mid-ship in the drive-line? How much torque are they good for? Can it be shifter on the fly or do you have to select the gear ratio and shift while stopped?
Al

 

Chelsea is the manufacturer of the power take off units mounted on the side of a truck transmission, depending on how old of a truck there is,Watson was the maker of an aux trans and a little later ****er made the aux units,depending on what ratio set up the box is weather you can shift all the gears on the fly, but yes you can shift while moving, many of the early boxes had square teeth and took a little more time to shift, much like the early Chevy non scenro boxes.
Need the model # off of it to determine what it is.

 

Thanks for your reply. The Model Number on the ****er/Dana/Chelsea aux box is:
4800 074 133, I think this box is from the 70's. I would like to find some original installation and set-up information if possible. Can anyone help?
Al

 

Odd ball number, post it over on the just old trucks board we've got a couple guys pretty good over there with the books.