Re: Pickup Magnet question...
Pretty much all of them are made in China now due to environmental laws.
I can't say whether this or that 'brand' of Alnico will hold a charge better or worse, but in my experience using a bunch of them from different makers, there doesn't seem to be any noticeable difference to me.
That mofinco finds a bunch of them with different gauss readings just means that some are not as fully charged as others. They may all have been fully charged out of the factory but between there and getting into your pickup, they may have been exposed to other magnetic fields, which can weaken them and also cause a bar magnet to be unevenly charged along its length.
But none of this is really a problem because Alnico magnets are easily recharged. A couple of neodymium disk mags in a steel vice with opposite poles facing each other = instant magnet recharger. Alnico 8 bar magnet = instant partial degausser/weakener.