The bolts are badly rusted and two have rounded heads.

ACE, Lowes, Home Depot. Make sure they are 8.8 or better.

My local Ace hdw has metric. Online is Belmetric and another I can't remember right now.

Belmetric.

The local Ace has single parts in bins The Lowes and Home Depot went to bags of hardware and not much of a selection. By me anyway, YMMV.

Thanks ! Ace is the Place….,

What size bolt for the larger front bolt ?

My local ACE is limited on metric, especially lengths. I usually can find something that will work, but isn't the exact right part. I usually look up the correct size in the PET and then order the exact match and finish through Belmetric.

Looks like #2 and #9 here

Click to view attachment

so M12 x 1.5 x 80 — Pretty long, McMaster only goes to 70mm. Pelican has genuine Porsche for like $14 a bolt.

The smaller are 8mm x 8, presumably 1.25 pitch.

Thanks Nathan
Why is that bolt 80mm

I think it is 9 and 6 that hold the cover on. The M12 x 80mm holds the support beam on and is a 19 mm head size.

Ah yeah that makes sense — I just checked my project and the bolts into the frame/car are 10 mm and the ones into the auxiliary support/crossmember are 8 mm.

Go with SS if you can & don't forget the lock washers. Flat washers may be necessary too depending on the cover holes.

Looking good!!! My car was undercoated like yours.

Done, Ace had everything. Problem now is to get the old bolts out. It’s awkward getting at them from the floor;the head of one M8 is wearing away plus a tough angle.

Vice grips & maybe PB Blaster too.