Step up step down transmission.

In an earlier post I questioned my auxiliary transmission type I misnamed a hi-low. According to my repair manual, Ford offered two types of auxiliaries, a Sherman step down and a forward-reverse (I may have the descriptions wrong) and my question is how to tell difference and how to use to best advantage. Also the drain plug is a 7/16 and I cannot get it to budge. Will I have to remove gearbox to drain? Sorry 'bout photo. I couldn't keep my arm still. Too much coffee.
Thanks
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The link below will help you identify the various types of Sherman transmissions.

Dean
John Smith Sherman Transmissions

First off, does the model number stamped into the flat spot on the bell housing say 841 with an "S" at the end or just 841. That will tell you whether it came from the factory with the auxiliary transmission (with the "S") or if it was added later (no "S"), which could have been done by the dealer or by a previous owner.

Secondly, Sherman made several auxiliary transmissions for Ford tractors, a step-up, a step-down, a combo with both step-up and step-down, a reverser and a creeper, which was like a step down but with a much greater gear reduction ratio.

As other said in your previous thread, it will most likely be a "combo" with both the step-up and step-down ratios along with the stock 4 speed ratio, as the step-up and step-down were generally only put in the earlier N series tractors, and by the time the '01 series were out the most common ones were the combo for ag tractors and the reverser for the industrial models for loader work.

How to tell for sure which it is?... Move the handle for the Sherman io the halfway point between its forward and rearward range of motion and pull out sideways on the handle away from the transmission housing, and if it moves in that direction then it is the combo. Then once it is in the "out" position, pulling the handle back toward the rear of the tractor will put it into the "stock" ratio with neither the step-up or the step-down gears engaged.

As to how to use it to the best advantage, what type of work are you planning to use the tractor for? Any PTO driven implement will need the same ground speed in any given gear on the main transmission to achieve the proper 540 rpm PTO speed no matter whether you're using the step-up, step-down or stock ratios on the Sherman because the Sherman changes the speed at the input of the transmission and the PTO is linked to the transmission input speed.

Maybe this will help?

http://www.oldfordtractors.com/sherman.htm

unless you drained it, it should have oil in it.

If you go back and look at your other posts you have been told the step up and step down or the over drive or under drive do not fit in the 841. But the combo which is a 3 speed and the reverser fit so likely the be a combo as said before

thanks
good advise much appreciated.

I did not drain the auxiliary but I did drain the tranny and the tranny oil had lots of water and sludge so I am assuming the auxiliary would have similar. That's why I wanted to remove drain plug but it's proving tougher than it looks.

parallel jaw wrench usually works

2 shifter rail up top. Is a combo making your tractor a 12 speed.

The stamp is 841-S so that clears that up. Thank you for taking the time to respond. Your advise is greatly appreciated.