Welcome to the forum!
The service literature available for your locomotive unfortunately does not have the parts breakdown for the front or rear trucks.
Call Lionel customer service at 800-454-6635 or 586-949-4100 with the model number of your loco, and ask them if they have the parts you are looking for, or the whole truck in stock. If not, they may be able to direct you to a parts dealer that does.
Larry