I need advice. The PO replaced the stock mirrors with Talbot racing mirrors and I want to reinstall the stock mirrors. The problem is that he drilled through the stock backing nuts in the doors to get the mounting u-bolt in!
What would be the best way to re-mount the stock mirrors?

You may have to shop for longer stainless fasteners, remove the vent window and install the mirror with nuts on the backside.

The vent window isn't hard to remove. Pull the trim card. there are two bolts through the door below the vent or corner window. Then remove the nut holding the vent window adjuster at the bottom of the door. Then remove the vent window adjuster from the bottom of the forward glass guide attached to the corner window. This will allow you to pull the corner window up and out of the door. You will then have a fairly clear access to the bottom of the mirror support.

Any suggestions of a source for stainless steel screws?

Do you have a local hardware store that has a 'Bolt Room'? If so, determine the length you need and take a stock screw in to see if they have a head that closely matches. Don't forget your nuts

www.boltdepot.com

Depending on the size of the drilled holes, you could also try to get some Rivnuts to put into the holes and then have new threads to use.

McMaster Carr is an excellent source for fasteners as well, but you have to buy larger quantities.

pic of stock bolt

The stock bolt is the same as the ones used to hold the door striker plate in the door jamb.

That's nice to know. I never noticed that. The closest I have been able to find at the local Ace have flat heads not domed like the stock mirror fastener.

I love little tid bits like that!

Garold is a wealth of knowledge. I've seen his driveway and garage. He's earned it.

I don't currently have the stock mirror screws. Does anyone happen to know the diameter and thread count on those screws?

I found SS screws and nuts at my local Lowes - but I didn't use Metric threads (since the stock threads are destroyed, you don't have to use metric either).

Use cage nuts like shown in the pic.

How do the cage nuts work? Do they hold on to the sheet metal?

I believe it is M8-1.25. Bolt depot is a great source but you do have to buy in volume. Way cheaper that the hardware store

David

it works like an anchor bolt. Be placed in the hole from outside, becomes fixed while you tighten the bolt. No need to remove door panel.

M6 x1.0 is the OEM screw threading

What kind of shape are they in? I'm interested in a set of Talbot/Durant style mirrors.

or - maybe - if you weld, buy this small section of a door and graph it in. plenty of people cutting up 914s.

are you just doing drivers door?