You need 256Kx9 RAM - 30 Pin SIMMS (not 128Kb as in your last post).  Best to have the 9 Chip versions (256Kx1 bit), but the 3 Chip versions should also work ( 2 256Kb x 4 bit & 1 256Kb x 1 bit).  8 chip or 2 chip versions will not work.  I am sorry but I don't of a good source for them, they were commonly used in late 1980's 286 & 386 PC clones.

Also, you will notice  jumpers to unable the banks on the SUN board, make sure they are set correctly.

HTH,

Rick