With 25.5" tires and the standard 2.76 gears, 65= 2368@ zeroslip, say up to 2440 on the tach. Kicking it down manually should get you ~3600 which, while not screaming, is easily noticed as abnormal.
More likely is that First gear is not working, which would be really sluggish on take off.
Occasionally the Second gear band goes so far out of adjustment, that Second gear no longer works. There is an adjuster, on the side of the trans, that you can get to from the outside. Unlock the lock-nut, lightly tighten the bolt, then back it off ~2 turns and see what happens. If this gets you going, somebody will get you the exact procedure; which, for a DD, is not nearly as critical as some say.
If the bolt will not tighten up;
the anchor may already have fallen out, and the only way to get it back is to drop the pan, find it, re-install it, then adjust the band.