You have two options, you can either replace the factory unit with a “double din” unit like what is there, or replace it with a “single din” (standard smaller size) unit and fill in the extra space with a little storage cubby-hole that any radio shop will also sell.
If you buy from a place like Best Buy the price usually includes installation, there are special little keys needed to release the factory unit from the dashboard.
However you can often get a newer unit from a similar van off a sales site like Kijiji or from an auto wreckers. This gives you factory plug & play with wiring and likely a more ‘factory’ appearance.