S4048-ON MIB file

Hi, I am looking to configure specific test monitors via SNMP for S4048-ON devices.  Can you please help me find the exact MIB file needed for this?  I have seen from other forum posts that all Dell MIBs can be downloaded from,

ftp://ftp.us.dell.com/sysman/

However, I am having a hard time finding, which file I need.

Thanks,

NICK