2003 C Custom - replace radio/cassette unit?

Some experienced advice would be very much appreciated here!

I'm very close to getting a low mileage 2003 Century Custom for my daughter, but... at present it has AM/FM/Cassette. No way, says daughter: CD, not cassette (and I agree). The question is this...

How time-consuming is it to swap sound units? I'm thinking I could tell the dealer it's a sale IF they pull out the cassette version and stick in an OEM AM/FM/CD. If it's not a big job, I'll make no special offer of extra money; if it's time-consuming, I'll offer to kick in a few extra bucks.

Swapping a CD Head unit out for the Cassette is very easy. If the dealer doesn't have 1 on hand.....Just buy Her a $100.00 Pioneer CD Player, a Mounting kit and wire harness adaptor for a 2003 Century custom and install it yourself. The whole project can be done in 1 Hr.

Swapping a CD Head unit out for the Cassette is very easy. If the dealer doesn't have 1 on hand.....Just buy Her a $100.00 Pioneer CD Player, a Mounting kit and wire harness adaptor for a 2003 Century custom and install it yourself. The whole project can be done in 1 Hr.
Thanks. I figured it was relatively easy -- nice to have that confirmed. I'd want to keep it stock OEM; I figure if they want to make a sale, they'll dig one up.