MF 165 Diesel Alternator wiring?

[dlinmi]

I have a 165 diesel that had been converted to an alternator prior to my purchase. It has a GM 3 wire alternator with a built in regulator. I've tested it at the large post and it is working but must not be wired properly because the battery runs down. The only gauge that appears to work is the temp gauge and tach. It has a two wire push button ignition switch. Anybody help me wire this to charge the system? I'm open to replacing the oil pressure and ammeter, or should I install a voltmeter? I've searched and searched but can't find my identical situation. From what I've seen the wiring is different ammeter vs voltmeter and gas vs diesel and wiring the exciter wire. HELP! Thanks Also, how do I get the ammeter out of the dash?