Hi It seems to me that if it substitutes for an eight track it should fit in any eight track player.  I've got s couple of those cassette to eight track adapter and they are universal.  The critical part would be how the output interacts with the players head but again they were made to take all eight tracks.

Could we get a look at the back side?

Maybe it is designed to fit a four track which I believe Muntz offered.

If it is a radio it would likely need some batteries to power the output.  More than likely double A's

Also I noticed that your picture background kinds of shows some financial numbers you may not want anyone else to see.

Probably not too much help but maybe...

Here's the tape side of the cartridge, notice the 5 contacts on the right hand side.   I'm pretty sure this needs to work with a specific set of Muntz players.

From the ad I would say the MPX -130 was part of, and inserted to work in the Muntz C-130 8 track unit.

https://www.radiomuseum.org/r/muntz_ster_fm_stereo_cartridge_mpx_1.html

FM Stereo Cartridge MPX-130

Model page created by a member from A. See "Data change" for further contributors.

Other Muntz equipment

https://www.radiomuseum.org/m/muntz-ster_usa_en_1.html

What is MPX-Multiplex ?

When FM stereo was being introduced around 1960, some FM tuners and receivers had connections for an optional FM multiplex decoder.

This was a separate unit that would take the signal from the FM detector, decode the stereo signal, and output two stereo channels.

On some systems, a stereo amp was already in place, on others, you needed to buy another amplifier channel and speaker if you wanted stereo.<P>

If you have a small unit plugged into your FM multiplex jacks, that's the decoder.

If nothing is plugged in there, you have a mono system.<P>The term "multiplex" simply means "multiple channels at once" (in this case two, of course).

A 38 kHz subcarrier is modulated with the *difference* signal between the left and right channels.

Therefore, if you add the signals from the main mono FM modulation and the stereo subcarrier, you get the left channel,

and if you subtract them, you get the right channel.

A mono receiver simply ignores the 38 kHz signal, leaving you with regular mono audio.<P>------------------<BR>Tom AE6XD

Are you thinking of putting it back into service Clint?

I have one of those old Audiovox under dash FM tuners that go through a AM radio.

The Brandon Sun got back to me with a copy of their June 14 1973 paper.   I kind of like the Model M-607 that has a built in AM receiver, and it accepts the MPX-130 FM Cartridge Tuner.    Now the trouble would be finding a M-607.

DonSSDD wrote:

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What year did fm come standard in most cars? What year did cassettes replace 8 tracks?

Fm was optional in gm in at least the early 60s, probably am fm was standard by early/mid 70s? Cassettes were same time period?

We now have no am radio signal around here.

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 I had a 1979 LeMans with a factory am/fm 8 track, and on the other end of the spectrum a friends dad ordered a 1971 Chrysler New Yorker and wanted an 8 track radio but the salesman ticked the wrong box on the options sheet. It came with an in dash am/fm radio and a floor mounted (on the hump) cassette player. I dont know when am/fm became standard equipment, but I am thinking late eighties or early nineties. Unless you bought a Hyundai Pony, am/fm cassette was standard equipment  

Paul

I got the M-888 player in the mail a couple days ago.  I powered it up, put the MPX-130 cartridge in and it worked.   I'd already had the cover off the player, and found the belt was deteriorated into just a few small pieces.

The player needed a bit of attention, as the volume and tone controls were very dirty.  A few squirts of contact cleaner smartened them up.   While the MPX-130 cartridge is installed, the motor doesn't turn, nor does it display what track the player is on.  I think that's by design.

Once an 8-track tape is installed, the motor turns and it displays the track.   The button to change tracks didn't work, but again a little contact cleaner got it going.   I spun the flywheel as quick as I could, and it's advancing the tape along, and I could hear some unintelligible audio.  So we're a step closer.

However, I need 2 things:

- a belt for the ability to play tapes.  From what I can tell the belt is 11.7" long, 0.21" wide.   Anyone have a source for belts?

- a male plug for the wiring harness.   Right now I'm using a pigtail from another unit.  Anyone have some old audio bits and pieces from the 70's laying around?    4 or 5 pin will work as I don't know what the middle pin does.

All of this stuff is really neat and fun to play around with and looks real cool in your car. But in the end it is not something you really want to play music with because of the hideous sound. I grew up with 8 track and had a few before i went with the better sound of cassette. They still are a cool look in any 60's and early 70's car. By the mid 70's the cassette killed off the 8 track. I am presently looking for an original 1974 Chevrolet AM FM 8 Track player for my 74 Caprice Estate wagon. Any one know of any around in usable condition.