Yes they do sell kits for 2 din, but some guys like the factory look which using Bravada or 2002-1/2 up GM parts can provide.Do they not sell dash/install kits for single and double din radios? Pretty sure they do.
Gm made a lot of changes around 2003 to it's truck radio line. One of the major changes was to prevent theft by pairing the radio to the vin and PCM. They can be reprogrammed or you can buy ones reset to pair upon installation. They are also connected to the PCM with some data lines.
For a 98 you'll probably be better off with an after market radio or one from a later S10. Double din is possible with the right kit or Bravada or 03-04 S10 or Blazer parts.
Just be sure any used radio you buy is unlocked.
If you are putting a factory radio from another rig in the truck then there is a way to unlock it and have it tied to your truck, there are a few videos and how-tos out there on how to do it.i have 2004 and im doing same, where do i find correct equip?
is there a way to bypass by swapping pinouts?