If I remember correctly, there were even some 286 motherboards with SRAM cache onboard, as well as on 386 boards. That would be L1 cache on those. For a 486 board, this would be L2 cache since the CPU has its own internal L1.

These SRAM chips were dual-inline pin packages (DIP), i.e. those black rectangular chips with fat pins down both long edges. Sometimes these were in friction-fit sockets and sometimes soldered down. On the 286, I think the DRAM was also socketed DIP.