I removed the grill and driver's side headlight as well but did not remove
the instrument panel.

I removed the ashtray to access the clips that hold in the radio. I pressed
the clips inward, then slid the radio out about half way. From the ashtray
hole, you can see the antenna connection to the radio (it looks like a
black coax cable).

I tied a small string securely to the antenna connection, then gently
pulled the antenna cable from the opening near the driver's side heatlight.
After a series of gentle back-and-forth pulls, the cable came entirely out
(with the string), and then I removed the entire antenna from the body. I
believe there is a rubber grommet that should also be removed and slid onto
the cable of the new antenna.

I then bolted the new antenna onto the body. Prior to this, I added a small
amount of clear silicone all the way around the hole on the body so that
there was a complete seal with the new rubber grommet betwen the antenna
and the body. I then tied the replacement antenna cable end securely to the
end of the string at the driver's side headlight, then fed the cable as far
as I could into the hole in the body. Then I went into the cab and gently
pulled the string until I could see the end of the antenna cable. In my
case, I used an adapter (from Crutchfield) to convert the replacement
antenna cable end to the kind that came with the OEM antenna, but you could
always splice it as well.

That reminds me: I have a brand new Hirschmann AUTA 970 B fully retracting
antenna that I no longer need. It's a front left mount and fits like the
OEM model, except that it would require splicing or the adapter from
Crutchfield (part 097 DIN3) if you're using the OEM radio. I believe this
is the same model that GoWesty sells under part number 251-035-503OEM. $20
plus shiping if anyone needs it.

- Kevin