In the process of removing my transmission and came across this. Car has a 5 speed 280ZX transmission. I initially thought the PO just did a poor job of swapping it over but upon more research the section that is cut back shouldn’t exist.
 

Anyone know why there’s seemingly an extra panel and bolt holes? 

Is there a tab in the tunnel that mounts the body side of the clutch slave cylinder fluid line?

43 minutes ago, CCB said:

Anyone know why there’s seemingly an extra panel and bolt holes? 

Good question.  Perhaps they're used to secure the special finisher plate used on cars with the automatic transmission?

The cutback in the tunnel sheet metal was a common solution for those who installed 5-speeds.  As it stands, you may find that your knuckles come close to colliding with the dash trim when you select 1st, 3rd, or 5th gear.  One solution is to fabricate a modified shift lever with a 'S' bend down low so that the upper part of the lever is moved about an inch to the rear.  This will also allow the sift lever to better align with the outer shift boot.

The 'extra' plate is, I believe, just a doubler sheet, used to provide a little extra stiffness for this region of the transmission tunnel (otherwise weakened by the cutout for the shift lever). 

1 hour ago, Namerow said:

Good question.  Perhaps they're used to secure the special finisher plate used on cars with the automatic transmission?

Right on the money! Feel dumb now, didn't even occur to me that the automatic was an option 🙃

The tab I referred to in my post was also absent on automatic cars. That why I asked. You might want to check that too.

Stock shifter will not work as-is with a 5 speed without interference. Most modified the shifter.

That plate was there on my 78 before I made the conversion. Definitely for the automatic shifter mounts. You have to modify the shifter with a torch. Not sure why they didn’t cut off the flap instead of folding it over.

Edited April 29, 2024Apr 29 by Yarb
Adding text

6 hours ago, Yarb said:

Not sure why they didn’t cut off the flap instead of folding it over.

It's possible that it was left there so that it could be bent back into place and welded/finished so as to return the car to 'stock' configuration at some point in the future.

Or maybe it was just laziness.

15 hours ago, Patcon said:

The tab I referred to in my post was also absent on automatic cars.

You say, 'also'.  Were the 4 captive fasteners installed only on cars fitted with automatic transmissions?  And the doubler panel as well?

Edited April 30, 2024Apr 30 by Namerow

16 hours ago, Patcon said:

The tab I referred to in my post was also absent on automatic cars. That why I asked. You might want to check that too.

Confirmed that tab is absent. Pic for reference

So your car started life as an automatic.  I had to add that tab when I was doing body work. I will have to look closer at my shifter hole to see what's there

You also will not have the metal stantion welded to the firewall with the rubber bumper attached for the clutch pedal.