Top Dash Panel needed

Define "top dash cover". Is it the top part where the holes for the speakers and defroster come out? (dash pad) or

is it the cover for the instrument panel?

Those covers are getting a bit long in the tooth. If it is the dash pad you need to replace, you might get lucky with a replacement from a salvage yard, or just order a pad cover from your auto parts store. Mine looks great, and I'm keeping my dash pad protected from the Florida sun.

I need the top plastic part that goes from the defrost vents down to the separate black panel that surrounds the instruments. There's a small crack in the area above the glove compartment, and fixing it means replacing the whole top section.

Ouch! You could try filling the crack with a vinyl repair kit (as seen on TV), followed by the addition of a nice looking velour dash pad. It is a LOT less money and effort than buying a new dash (Big money) or the salvage yard (somewhat less money)