Satellite radio will be my fathers day gift from me to me. Ok, you audio nuts, I want to find a unit that is going to fit in the cassette space of my '89 after taking the door/faceplate off. Any solutions for type/ brand/fit. Obviously I want it to look like it came from the factory that way! Is it possible to have the antennae mounted somewhere other than on the sheet metal?

Realistically not much is going to look or integrate like factory. I'm sorry about that. The best option would be something like the Starbase Tuner (http://www.tss-radio.com/sirius-starbase-scfm1-tuner-system-p-117.html). It will connect using an FM Modulator that would connect thru your FM Antenna. It would give you good sound quality and it's pretty discrete to hide. You would have to mount the antenna somewhere on the outside of the vehicle or you might be able to get away with mounting it inside the windshield on the dash. I can do that in Chicago area because there are a lot of repeaters which increase the signal to SIRIUS XM. But most people will simply have too many dropouts with that method.

Is the antenna small enough to mount on the small strip of body between the rear of the convertible top and the front of the trunk lid? It would also have to be low enough to clear the open trunk lid and open hard boot.

Is the antenna small enough to mount on the small strip of body between the rear of the convertible top and the front of the trunk lid? It would also have to be low enough to clear the open trunk lid and open hard boot.

I don't know because I don't have an Allante to try it out with but the antenna is about 2" by 2" and an 1/2 tall.

2" x 2" is too large for that narrow strip. It can probably be mounted to the front edge of the trunk lid assuming the 1/2" height doesn't interfere with the open hard boot.

You can mount a small XM antenna (about 2"x2"x1") on your dash at the base of the windshield. It has a magnetic base that locks it to a speaker grill I have at that location, but it can be mounted with supplied double-backed tape. The only stock option I saw for the XLR was the ugly OEM "wart" antenna that mounted on the rear decklid and required drilling through it for proper mounting.

I bought an antenna through Crutchfield-- http://www.crutchfield.com/p_209XMICRO2/Terk-XMicro2.html?search=XM+Installation&tp=149 wired it in to ensure it would work at that location; tested it thoroughly in different orientations with the top up and down, then permanently installed the cable. It works like a champ and is virtually invisible.

I hope this helps you.
CC

something along these lines