Thanks to all for the answers/suggestions.
I will be doing the American Freedom Train (using Flyonel, S helper and American Models) - no problem there.
Also the Reading Rambles with American Models passenger cars - no problem there as well.
It is the coal drag with mainly old Flyer hoppers and a few gondolas and box cars that will present the problem. For a buck/fifty per set, I'll try the bushings - if they improve the situation - GREAT, if they don't - at least it didn't cost alot.
If the bushings don't work, I may be forced to purchase new trucks. - that would be expensive.