During the lifetime of the MAXen, there have been several enhancements in chip design and modem technology.

One major player was Rockwell. The first integrated chips have killed all discrete designs like the very well known Zyxel U1496 with its perfect working standalone Motorola 68000 CPU and these new chips pushed the market with mass of external and internal modems.

Ascend did develop its first plugin card MX-SL-8MOD-V34 modem with up to 33 kilobit in 1994 based on a Rockwell chipset..

We know about the following modem cards for MAX 1800 up to MAX 6000:

Ascend MX-SL-8-MOD ( it seems to be named type I )
Ascend MX-SL-12-MOD
Ascend MX-SL-8-MOD-S56 ( it seems to be named type II )
Ascend MX-SL-12-MOD-S56
Ascend MX-SL-16-MOD-S56

the following models are designed for MAX 6000

Ascend MX60-SL-24M-S563 ( it seems to be named type III )
Ascend MX60-SL-30M-S563
Ascend MX60-SL-60M-S563
Ascend MX-SL-24M-DSP
Ascend MX-SL-30M-DSP
Ascend MX-SL-48M-DSP very rare
Ascend MX-SL-60M-DSP very rare

and there are some dedicated versions for MAX 3000 (not for MAX 6000)

Ascend MX30-SL-24M-S563 ( it seems to be named type III )

There are a lot of modem Cards for the MAX TNT, please check the sales price list.

Here is a sample for the latest "brand new" DSP Modem Card for the 6000 models, not running in other MAXen.

And take care with antistatic packing, the very last 24, 30 and 60 port MAX 3000 and 6000 modem cards are no more in a metal box, they are open without a cover ! And they have very few chips compared by the MX-SL-16MOD-S56.

: So this MAX 6000 is fully equipped with 2 cards with 60 ports each = toatal of 120 ports.