Looks like most of the dash has to come out. Probably why the previous owner just added one under the dash in front of the console and called it a day.

 

i did this along time ago when my speaker blew out. remove the duct work, i think the radio too. i was able to reach my hand up there a get the speaker out and original replacement back in. not the easiest but possible. hope this helps.

 

If you have a four speed console, A/C and a tape deck it is difficult...but if you have none of the above, then go straight up behind the radio, and if you find that hard, then take the radio out too...