I will take a stab at this...as I have a 250A...and my manual is for the 250AS. The 250A has a single shift lever which handles high and low range, forward and reverse as well as the 8 forward and six reverse gears. The AS model has a second lever that exclusively shifts from forward to reverse, leaving high and low range and the various gears on the second lever. On my A model I must first select forward or reverse...and then the actual gear that I want.
My first post here...hope it helps. I can take a photo of my A pattern if you need me to.
Kim