mac5019

I may need to get a few of these for Aristo engines I have. I am new to G and have a few questions on installing the Bachmans. As I understand it the older Aristos will need an A frame installed to make this work as the earlier ones used extended axles to fit into side bearings to hold the blocks in. The Bachman blocks don't have the protruding axles and must be mounted with an A frame So how do I install an A frame if needed? I read an article on it but it seemed a bit complicated I would appreciate any info on this!\ Thanks!