Battery hold down.

[T Ames]

Hello Bill. Here is an excerpt from the 2017 rule book, Paragraph 8.1 in the General Regulations section. It looks like 2 - 3/8 bolts required OR complete OEM hold down with original hardware but no "J" hooks permitted.:

8:1 BATTERIES
All batteries must be securely mounted; must be of sufficient
capacity to start vehicle at any time. Batteries may not be
relocated into the driver or passenger compartments. Rear
firewall of .024-inch steel or .032-inch aluminum (including
package tray) required when battery is relocated in trunk. In lieu
of rear firewall, battery may be located in a sealed .024-inch
steel, .032-inch aluminum, or NHRA-accepted poly box. If sealed
box is used in lieu of rear firewall, box may not be used to secure
battery and must be vented outside of body. Relocated battery(s)
must be fastened to frame or frame structure with a minimum of
two 3/8-inch-diameter bolts. OEM located batteries without
complete OEM hold-down hardware must be secured to OEM
battery box/tray using the same 3/8-inch-diameter bolt hold-down
method described in previous sentence. (“J” hooks prohibited or
must have open end welded shut.) Metal battery hold-down
straps mandatory. Strapping tape prohibited.