[Amps] Meter replacement

[Kathy Bookmiller via Amps]

Hello,
I'm fixing up an old Hunter Bandit 2000C. It has one problem left to solve and that is to replace a smashed panel meter. The one that measured plate voltage and current.
The original meter was made by Ammon instruments of Manchester NH. It has am-2 on the face plate, which I assume was the model number.
I found two Ammon meters on Ebay that are the same size and style physically and one of them even has the same am-2 on the face plate (the other one's picture doesn't show this)
I guess my question is, how does one know is this meter will be the same movement. At one time I knew this stuff, but years have dimmed my memory of meter shunts, etc. Out of curiosity, I put my VOM across the terminals of the broken meter and it measures 90 ohms.
What I hope to do is replace the face plate with my old one and have one that matches the style of the other meter that is used for a watt meter. 
The old one's scales are for 0-3000 volts and up to an amp. current.
Anyone still remember their analog meter theory and practice?
Thank you,
Kathy, W2NK