Differences in SNMP results between versions

Hi all,
I have been tasked with creating a new NAV (3.9.1) install. All appears 
to be fine until I compare it against the previous old (3.5.4) installation.
The majoirty of our switches are Cisco 3750's nearly all stacked, but 
the new install doesn't seem to acknowledge this under 'IP Device Info' 
where the 'Modules' field shows '0', but the 'switch port status' table 
shows all interfaces spanning the stack.
On the old install the 'Modules' field has the correct number and the 
'Switch port status' shows the right number of separate modules.

Looking under: 'Report-> Vendors -> Cisco' confirms that the new install 
is receiving less SNMP OIDs per switch stack; typically 75. Where as the 
old install is showing between 88-90 for the same stacks. Also in some 
cases the new install is not showing any returns under #mod, #swp, #gwp 
and #prefixes, where is does on the old install.

Both installs are running libsnmp1.4-java; the old 1.4-5,  and the new 
install 1.4.2-2.
Would that account for the differences? What's the best way to test the 
two installs side by side in an output based comparison?

Many thanks,
seb.