Are there any survivng cars (in museums or otherwise) with this type
of truck? As a relatively attentive observer - I don't think I have
ever seen a truck of this design.

I think Portola has a WP 53' gon with National B-1s under it.

Are there any survivng cars (in museums or otherwise) with this type
of truck? As a relatively attentive observer - I don't think I have
ever seen a truck of this design

I took several pics last July of a Pennsy G29 gondola in captive service at Standard Steel in Lewistown PA. This particular car has the 70t National B3(I think) but they look identical. I posted the picks in a file in the Steam Era Freight Cars Photo group, look in the foler titled Surviving PRR Gondolas.
Roger Cox