cpuid from here can help you find its version very quickly from 98se https://soggi.org/misc/tools.htm
I use the date and year to track down driver generations

nVidia has unified drivers for (non-mobile) chipsets. Anything that supports TNT2/M64/Vanta will work. Generally you want the oldest = lightest drivers you can find that supports your needs (DirectX version). Everything from Detonator 2.08 should do the trick, although if you want DirectX 7 you need Detonator 8.05 or newer. Anything beyond that is pointless as a low-end TNT2-variant won't be able to sensitively use it.

I think this is one of those universal drivers you're talking about dionb. I reckon I'll give it a try since it's the official one nVidia says to use:
https://www.nvidia.com/Download/driverResults.aspx/12/en-us

You can find every Detonator driver you need for a tailormade TNT system here:
http://vogonsdrivers.com/index.php?catid=24

Snookeroo wrote on 2021-07-29, 11:36:

I think this is one of those universal drivers you're talking about dionb. I reckon I'll give it a try since it's the official one nVidia says to use:
https://www.nvidia.com/Download/driverResults.aspx/12/en-us

Thats a very late, very heavy one (Detonator 71...). Unless you have that M64 in a late P4 or Athlon64 system, that driver will slow it to a crawl, and even in that case it won't offer added value over a much older one.

There are much earlier ones on the nVidia site too, but Vogonsdrivers or Phils Computer Lab archive the most useful ones - all official nVidia releases too.

Thanks so much for all the advice guys.

Which one should I use from this list?
http://vogonsdrivers.com/index.php?catid=24

Is my card Riva or Detonator? Will I have to remove the heat sink to tell?

Detonator is driver, not graphics chip. Your should be Riva TNT2.

Excellent, I'll give this one a go and keep you all posted on how it goes!
http://vogonsdrivers.com/getfile.php?fileid=274&menustate=0

Cheers for the help guys. Saving my skin as always!