I believe a 42 to 48 car spindle is the same ... but I could be WRONG
I would call Dick Spadaro ... he sells parts, is very knowledgeable and most of all HELPFUL.
Tech Line: 518-861-5367
He is in New York state.
I have a couple pair of 48 to 52 F1 spindles but I do not know if they are the same as yours. I just started messing with the newer stuff ( like late 40's ) recently.
Here is my current project.
It is a 1949 Mercury 1/2 ton pickup.
Only available when new in Canada.