I'm becoming a big fan of Triplett meters. Their large-meter VTVM was the model 850.
Triplett model 850 VTVM
BAMA has a scan of the Triplett 850 Type 2 manual, but it's of poor quality. The Triplett web-site has a much better quality scan, but Jewell seems to randomly remove files from their site, so the link might rot.
Triplett also made a similar VOM, the model 800.
Unfortunately mine is missing one knob, the handle, and the probe. Anyone have an extra probe?
Fred Scoles, an expert in the history of Triplett, tells me that the 850 was pretty much a copy of the RCA WV-98A Senior VoltOhmyst VTVM. (Simpson's model 312 is their version of the RCA WV-98A.) You can compare the schematics yourself:
Triplett 850 schematic
RCA WV-98A schematic
Simpson 312 schematic