Some newbie questions:

I bought a 1985 300TD a few months ago, in great shape. However, since this is my first Mercedes Diesel, I have nothing to compare it to, so I want to make sure that it's running okay. Specifically, it seems like it should have overdrive or something of a top gear from where it tops out at. At 70MPH it's running about 3k rpm. Is this normal?

Also, normal operating temp is to be about 85 deg. C, but when punching it (above 70 mph) it gets up to 90 deg C.

That seems kinda high to me... Can anyone verify these things on their automobile?

Thanks,

John