All correct opinions except that the Allison 3000 and 4000 series lock up at higher RPM in SECOND gear, not first gear.
And as you can see, you can either "let it do its own thing" or you can use the up/down arrows to proactively choose a gear.
It will not do anything that would endanger the engine or transmission. Said another way, down arrowing to 1st at 60 MPH would cause the transmission to downshift one gear, until road speed lowered to where it was safe to downshift again-- all the way to first.
Particularly if you want to treat it like a manual transmission and YOU select the gear, push the MODE button which selects economy mode. That allows the engine to upshift earlier and downshift later (exactly what the engine manufacturers recommend for economic driving. Then if you see a steeper grade, use the down arrow to select a lower gear.
OR, if you want, just let it in "D". Gears and gear changes will be OK, but not ideal, since the transmission is REactive (responding to what is behind you), not PROactive (responding to what is in front of you).
