It's even more rare to get an MT-32 with the right serial number though. I play games mostly through DOSBox so getting one without the buffer problem is important.
Hmm, I just purchased mine off ebay: item #290268701072
I didn't see any headphone jack on this. I'm guessing this is the first revision type. Would it be possible to mod the MT-32 to the 2nd or 3rd generation model or is this going to "Buffout" on me? To make a bad pun on Fallout.

Here's my current DOS machine setup-
Dell Optiplex Gs, Pentium I
32MB SDRAM
2 Gig IDE boot drive, 40 Gig EIDE storage drive for retro games
Windows 98, probably all current updates
(DOS 7.1 upgraded to this)
NVidia PCI 32MB GeForce 2
full-length Sound Blaster AWE32 with 16MB RAM on the card
one spare SB-16, currently not installed
2 empty ISA slots, probably 1 or 2 more empty PCI slots
cheap OEM Dell CD-Rom drive
noisy IBM PS/2 keyboard with retro curled cable
nauseatingly beige/off white case
Ball mouse
Beer