Blower motor nuts for an a/c car

[noschevys]

Can somebody check and see what size the original nuts are fo the blower motor attachment to the firewall on a 71 challenger with a/c?  Mine are 10-24, but the fastener guide says 1/4-20.

[FY1Cuda]

A '70 Challenger w/ AC is 10-24.  Just checked.

[noschevys]

Thanks,  Are they keps nuts? and what finish would be original?

[FY1Cuda]

Yes, they're keps nuts and our's are dull grey now.  I don't know if they were bright once.  I think the original Mopar keps nuts are a little taller than the ones you see now.

[noschevys]

Thanks!!