[Heathkit] Heathkit IM-18 meter mystery

[Dan Pividal]

I have an IM-18 Heathkit VTVM.
The problem is that it looks nothing like the one on BAMA when I downloaded 
the manual.
The one on BAMA has only one jack on the middle of the lower front of the 
case.
Mine has this but also has a jack on each side of the middle jack.
One jack is red and one is black and the are for banana plugs.
I noticed that the one on BAMA requires a special probe for the center jack.
I do not have that probe but regular banana plug type plug probes seem to 
work fine on those jacks that the BAMA manual for the IM-18 are lacking.
I want to use this meter to measure the 1500 volts dc that it is rated for 
but now I don't know if it is safe.
Anyone know anything about this.
It does not look like a modification was done.
Dan/N4VET