Can anyone help me out on installing a new head unit in an 88 929. Best Buy said it was to much of a "risk" to take the old headunit out. The unit has the equlizer and cassette radio, and it looks like it's one big piece. Is this a relatively simple thing to do or will this take some serious time?

Thanx in advance
~ Andy

I have the same car. email me and I'll send you the service manual page that shows how it comes out...

Hey, thank you just gave u an e-mail entitled "pics"

Page has been emailed. Please post again and share observations, questions, etc. I'd like to know if you have any success finding out how to wire up the sub-amp (I think it's behind the back seat panel, in the trunk, for the radio/cassette/equalizer, or under the dash for the radio/cassette/cd unit).
From the wiring diagram, it looks like there is a lead from the HU, but I never could figure out if it's a line level input or low level, like an RCA pre-out on a standard HU.

The factory head unit in this car (radio/cassette/equalizer) is a 1 piece unit that can't be disassembled, so you need to size the replacement accordingly. Look for a double din unit, or check Crutchfield for an installation kit. They usually have one.
Next, you will need to locate and mark the 4 pairs of speaker leads in the car, on the plug that goes into the HU, and plan on how to transfer them to the new unit. adapter kits are available, but it's often just as easy to cut and splice, marking each pair of leads with a taped tag (FR RT, FR L, etc.). This is nice for later trouble shooting, and also for the new owner of your car should you decide to remove the HU.
As posted earlier, you'll need to decide what to do with the sub-amp and shelf speakers. If the new HU has a sub-amp pre-out, this may work. Or, run the shelf speakers from your HU, if it has capacity for 6 speakers (total in the 88 929: 2 dash, 2 rear doors, 2 shelf).
Aside from mounting the new unit, and speaker connections, all that's left is connecting the antenna trigger wire if you have a power antenna still installed (note that OEM early Mazda antennas respond to a neg trigger signal, not pos, so this will require a relay conversion), and a source of IGN or ACC controlled 12V for power on.

Alright... got the headunit out of the car, although it wasn't as easy as I thought it'd be.

simple really, unscrewed a couple screws and took the headunit out, all one piece thank god then came the hard part... gettin all 6-7 little wires, or wires connected to wires, off of the unit's backside. pulled some of the wires out, which having to snip a couple other ones (Figured it'd be just as easy to get some splice action going on here), and unhooked 2 black cords that were deep inside the headunit, snipped those aswell because the headunit looked pretty bolted together.

But overall, this wasn't a difficult task, I don't know where Best Buy's "professional" installation was this time!?