So I’m currently missing the entire battery hold down assembly so I have that to figure out, but under my battery is a plastic spacer it seems. It’s about 1.5” thick and I can find no mention of it anywhere or in the parts catalog. I’m assuming this isn’t stock?

 

Correct, not a stock item. Battery sits on steel tray. In this photo, you may see rods with washers and wingnuts on them lying on the tray. There are four here but a car requires only two, one for each side of the battery. There's a steel frame that sits on the top of the battery--the threaded rods secure it in place.

 

I've seen some new batteries come with spacers like that so they can be used in various cars with differing heights or types of battery hold down brackets. Battery specific, non-OE.
Jon

 

I have an extra battery hold down tray from my 94 coupe donor vehicle.
Doesn't use the top frame to hold down the battery.
They always corrode faster than anything.


Uses a bracket that fit's into the bottom of the battery.
Really excellent condition.
PM me an offer including shipping.
Steve