Easy way to go is with an OEM Radio from ebay. Make sure you get
the code to activate it. An SC-816 model is what you want. There
are 6 up for auction now. In the past they seem to sell for
about $225 (U.S.). You want one from a 98 or newer since the front
bezel is a dark grey on 70 series and the older 850s it was a
dark black (although a radio from an 850 will work, too).

You can swap the two radios in under 90 seconds. To take out the
radio push in on the two slotted tabs at the lower corners. They
pop out and act as handles. Pull out, unplug cables, plug in
new radio (cables will interchanges) and push new radio back in, turn
on ignition and type in the radio code.

Make sure you have your old radio's code, too. The radio can't be
used without it.