help with dead 1938 cartridge

[dtvmcdonald]

I have an RCA u-10 radio phono. I bought it to use as
the amplifier-speaker of the tt5 TV in the Repair forum. It works nicely as that.

Now I want to get the phono working. The turntable works OK but will have
horrendous rumble (which won't get to the speaker.)

The cartridge is of course dead. I thought that you could get them rebuilt ..
and you can. But the one that came with it is apparently an unrebuildable replacement.

Thus I need a new one. Do ones exist that will take the horrendous
force of the heavy tonearm? I suppose I could add a counterweight.
The amp has lots of gain, 0.4 volts is plenty.

Similar heavy arms were used in all the RCA U-xxx phonos of the day.
What do people do? I really want this to work. It would of course
never be really used any.

Sorry if this has been answered ... but searches failed. This is also posted on the radios forum.