Fuse box circuit parts

Search for "terminal" with "piggyback" and either/or "F crimp" and "open barrel"
F crimp usually has the insulation crimp which you absolutely want in this application.
IMHO the open barrel type crimps, correctly made, are far better than the closed barrels.

AMP's "Faston 250" series is (or was recently) a product line with this type of piggyback.
You can also try looking in what's left of the Packard - Delphi lines. Its probably not going be under "56" Series because female 56 terminals use a leaf spring type design. The 58 was the rolled side design. Squared is probably yet a different series or some other manufacture.
One more hint. I've noticed in some catalogs the company calls female terminals "recepticles".

If you find a good source, post it here
Sources for Chrysler type wire terminals