Ah, the learning curve I faced just a few months ago.
As a general rule ,a semi truck uses a PULL type clutch that has twin friction discs and a clutch brake. A clutch brake is for transmissions that do NOT have synchronizers and gear shifts are made WITHOUT touching the clutch pedal.
My bus has a semi trans that I installed to replace the Allison at545. I do NOT KNOW what your bus should have, but from what I read they had 5 speeds that were synchronized. I ASSUME that a clutch for that application would NOT be a pull type, but rather a PUSH type like a car/light truck.
Either way, you need free travel which you get from the adjustment you have found. Just give that rod end about 5 full turns and test to see what your travel measures.