Amp Meter for A/C welder

[drivermark]

Hey Guys,

I have an old A/C buzz box that I would like to install a meter/gauge/readout of some type to indicate the amperage output.It is an old Campbell Hausfield unit that Walmart used to sell back in the '90's. The "indicator" it came with is just a pointer and to adjust amperage you turn a little crank/handle that makes about a turn and a half before the needle starts to move, so I have no idea what the actual amperage is.

So my question is ... How can I make, beg,borrow, buy, steal a readout (preferably digital but I'm not picky) that will indicate the amperage fairly accurately.
I've tried the search feature on the sight and Google but so far no luck.

Thank you in advance for any help on this.

Mark