There are two types used as far as I know, the first is a simple SIL resistor pack, typically 9 elements with a value of 110 ohms. Drives using this arrangement typically have two resistor packs
The second has two elements per pin, one pulling up to TERMPWR and one pulling down to GND, typically the pull up element is 220ohm and the pull down one is 330 ohm. Drives using this arrangement typically have 3 resistor packs
It's pretty easy to work out what kind the drive expects, you just need to test for continuity at the ends of each resistor pack to ground, if one end is grounded you need the second type, if neither ends is grounded you need the first type.
As for replacements, I believe the second type is actually still made (Or at least NOS ones are easy to find one eBay) the first type I actually found to be really hard to get hold of in the past (At least in the UK, it might be different elsewhere) you can substitute 150ohm resistor packs (which are easier to find) in place of the 110ohm ones and it will normally work fine but keep in mind this is not in spec so might cause issues in some circumstances.
