aftermarket rads for mahindras? none that i know of. I would get in touch with a good dealer that way you are sure to get the right radiator in case there are serial number breaks.
For kicks I looked up a radiator for 6500 4wd on mahidnrapartsonline and they show one for $335, not to bad IMO for a low production volume OEM radiator.
You could also see about getting your original radiator repaired.