I can't figure out how my ECU mounts on the battery tray. My battery tray and bracket mount holes do not line up.

This is for a '73. I did not replace the battery tray, but that doesn't mean someone prior did not. Is there another style bracket that matches this battery tray?

Click to view attachmentClick to view attachment

Can get a picture for you tomorrow, 75 -76 is welded on.

I have a 75 with a replacement tray. I think I remember drilling two holes.Look at the tab in the front and the screw hidden on the side.
Click to view attachment

Should mount this this

looks like you have a replacement tray, they're missing a couple of stock holes.

For reference purposes, does the ECU bracket make contact with the firewall or is there a space?

It's maybe 2" away from the firewall mounted on the side of the battery tray.

The Dansk battery tray is not correct. That is what is pictured. Here is what we make and sell:Click to view attachment