I don't mean to argue. Your 0.640" dimension may be correct on your part, but I think you'll find that it is actually 0.635" on virtually every Langair produced RV tailspring out there.
If you were to ream the tailwheel mounting housing to 0.640", you'd be very, very unhappy with yourself. Even 0.636" is too loose. Both spring and housing should measure 0.635"
Thanks Vince. It will be a bit before I can measure mine but was told I may have an issue, sounds like I may be ok though. I think my source who raised the yellow flag has something else he was using for comparison.
All good ACB. My other offline resource raised the flag and I was 1200 miles from him and my pieces and parts. I knew the data was close at hand here on the forum.