I need a linux (deb) driver for a Dynex modem model # DX-M100. I have had no luck getting it and have never heard of the name (which may just be my fault).

That appears to be based on the Intel 536EP chipset. There are a number of drivers for that modem chipset, and which work on Linux. Driverguide offers some, and also, I would check at Linmodems.org. Intel also makes linux drivers for their chipsets, which can be downloaded but *may* be speed-limited without paying something like $20.00 for the fast version. For the record, I used their cripple-ware driver for a while on another modem model, and it went just as fast as other drivers which weren't restricted.
For further information, there are a few threads on LQ here about that modem, and try Googling "Linux DX-M100"
I have had hit or miss success using dial-up modems with linux, but that chipset in particular, I had good success with.

All I can find is a tgz file. I would like a debian file. Or do I not need one?

Anybody out there?

Do I only need a tgz file for a driver? If so, how can I install it?

I went to www.dynexproducts.com and I called a representative, and he says they only have drivers in a zip file. (He said he knew what Linux is then explained how to install a zip file. lol) So, are you sure I need a 536EP chipset? I went to Intel.com and they have 6 pages of drivers. They are all in a tgz format.

Go to http://linmodems.org/ , do some reading, if this is a pci modem, download a small utility called "scanModem", and follow instructions on how to use it. There is a blue colored link on that page by that name, read the next page and hit the "scanModem" link again to download it and run it. It will tell you if your modem is supported and where to get the driver kit with install instructions.
If it does have a Intel 536EP chip, it is supported and you will get all the speed your ISP is willing to provide, only conexant pci modems have a speed restriction asking for money for full speed.
If your distribution is 64bit, only Lucent Win modem with mars chip set can be installed for a pci modem. Chip set # 1646t00, 1648t00, & agere 1648c.
If your modem is USB, click on the archives link on this page to see if you can find another case involving same modem and how to get it to work.

BTW:
Debian used to put together Lt modems (Lucent tech.) in a .deb package, not Intel. Knowing which distro/kernel you need this for would be great info. I did like GrapefruiTgirl and Googled your modem, it is a 536EP chip. The driver at Intel's site is #16 at the page link below, but the one from linmodems.org is probably better suited towards newer kernels as Intel stopped supporting Linux a couple years ago, but one of their techies is a maintainer at linmodems by the name "Phillipe Vouters" and has made slight modifications to packages to better suite more recent kernels/file systems.
But I could not access the linmodems driver archives to give you the exact link, maybe they are down temporarily, or for good, who knows. In any event, you may still run the scanModem tool and use the link it provides. If you run into "unknown symbol" errors during the make or install step, a hacker has found a way to get around that issue. Check my threads to see how to possibly get around those errors. I only have 3 threads, so it's not like you have to take a day off to go through them.
The second link is for the linmodems Intel drivers that I could not access.

http://downloadfinder.intel.com/scri...9&submit=Go%21

http://linmodems.technion.ac.il/pack...lippe.Vouters/