Really basic... any difference between SOHC and DOHC USDM S13 gauge clusters? If so, are they interchangeable?

Yes there is. Not interchangeable unless you take out the tac. The sohc redlines at 6 i think where the dohc redlines at 7(forgot but I know sohc redlines earlier) so you can replace your gauge with the other one, just make sure you swap the tac.

Uh let me clarify... :lol: I'm looking to swap in a KA24DE for my KA24E. Will I be able to use the existing gauge cluster or will I have to get the KA24DE cluster as well?

like i said you can use your existing gauge, however your tac will not work. You must get a tach from a 91-94 240sx as well as the ecu. The tac will not work if you use it on a ka24de engine. Your existing tac will redline at like 6 where the ka24de tac will redline at like 7.

speedo up to 115 on sohcs-110 on dohcs
also goes at increments of 10 starting with 5

sohc, = 5, 15, 25,...
dohc= 10, 20, 30, ...

Thanks guys :D