Monkey, Perkins panels
were fitted with VDO gauges in most cases. The senders have numbers stamped on the hex flats (Where the wrench goes) so you can identify them. The pressure senders have a resistence of 10 - 180 ohms o to full scale for a single
gauge application. They have moving parts
and can fail. The US standard is 240-33 ohms so do not mix brands. The temp senders use a thermister (no moving parts) and almost never fail. The tachs on the 108 are driven by the poles of the alternator
so changing Alts can change the rpm
reading. I have a VDO based panel in a boat built in Spain
in 1957 and the gauges still work. Check the wiring
grounds are critical.