I'm replacing the rear main seal and want to save my clutch because it's working ok. How do I know which clutch alignment tool to get? Does it differ by manufacturer?

Broom handle, otherwise princess auto (harbour freight in the states) has a universal clutch alignment tool

I might have an exedy one laying around from when I was installing clutches on my 2002. Have no use for it anymore. If I can find it, I'll let you know

You can also look on RockAuto, they sell them for like $5.

https://www.rockauto.com/en/catalog/...ment+tool,7700

There you go OP. The clutch alignment tool shouldn't be specific for a clutch kit, but rather for the transmissions for which that clutch kit is compatible with. Simply because the input shaft of the transmission needs to line up with the splines on the clutch in order to work. That said, any clutch that'll work for your car should come with an alignment tool that's spec'd for that tranny.

For the D17, the same clutch alignment tool should be compatible with basically any 92-05 D-series transmission