Has anyone put one of these in there classic car?
Didn't want to put the magnetic "puck" on the roof
going to try it inside at the upper corner of the windshield
is there any other options?

It will work somewhat in the windshield. It will work somewhat on the package tray. It just will not be very good. XM satellite radio transmits from geostationary satellites at the equator so you need a good view of the southern sky. Sirius uses satellites in elliptical orbits that are overhead for the most part as well as another in geosynchronous orbit to fill in.
Best results for XM would on the roof, next best on the trunk, third best on the package tray if you are always northbound, in the windshield if you are always southbound. Sirius may be usable on package tray and windshield.
Here in Colorado, they built mountains in the way so I did not even consider satellite. I put in HD radio into the 'Cuda instead. My truck came with a year of XM but I did not renew. I spent 4 years in the satellite uplink business as an engineer putting satellite TV, DMX radio and other programming seen and heard around the world.
Craig

Thanks I got sirius
going to try it out to night
had it on the dash but going under trees it would cut off
My ? is do they make any other inconspicuous transponder??

My SATELLITE has the stock AM Radio; never noticed any sort of "transponder"...

I have Sirius in 3 newer vehicles. They all cut in and out under a lot of trees.

I have Sirius in 3 newer vehicles. They all cut in and out under a lot of trees. All are mounted on the roof.

The black thing is a patch antenna with a built in preamplifier. No, I do not know of any that look better. If the antenna cable is long enough I would try the back package tray.
Craig

Thanks everyone didn't get a chance to drive my car yet
but I'll try in several spots.

In my 70 Sport Satellite, I left the original AM radio in the dash, and put the "hidden" stereo unit (guts of it mounted behind back seat, controller up under the dash)into the car. For the satellite radio antenna, I placed it UNDER the package tray in the middle of the back window - you don't see anything, and reception is totally fine - same as in my "new" cars ! When I say under the package tray, I mean that I put the antenna on the metal and then the black cardboard package tray on top of that. there is a few indentations in the metal that the antenna fit into, so there is no "lump" in the cardboard. Basically the sat radio isn't gonna care about the cardboard covering it, and it is looking pretty much straight out the glass of the back window.

Thanks I try that spot also