I had no problem removing 4 wheel trucks from RichArt 700 series passenger cars & replacing them with original Lionel 700 series 6 wheel trucks.
This is the 4 car RichArt set with 4 wheel trucks as I received them:
I removed the 4 wheel trucks from the RichArt set & the 6 wheel trucks from the original Lionel set & restored the beat up Lionel trucks so as I could use them on the RichArt set:
This is what the RichArt set looks like with the restored Lionel 6 wheel trucks:
I put the 4 wheel RichArt trucks on the beat up original Lionel cars for a future restoration project:
I bought the beat up Lionel set through an auction from one of the large auction houses with the intent of using the trucks for the RichArt set.
Once again, I had absolutely NO problems switching the original Lionel trucks over to the RichArt cars without modification.
Hope this helps.
Ken