My understanding is that if you are utilizing a
spool, you are required to leave the rear caps
OFF so that tech can determine that you are running
the required aftermarket axles.
The rules require that anytime you are running a
spool, you must have aftermarket axles.
Bad things happen when an axle breaks and you are
running a spool. I can attest to that fact: See chopping
down the tree literally or google John Irving Racer to
see.
Only good that came out of it was I made the covers of both
Hot Rod and Car Craft magazines the following month! Plus
center two pages of Car Craft and back page of Hot rod.
Only cost me three broken ribs and a surgery! I guess that is
a cheap price to be famous!.