Technical '40 Ford Body Mount Bolts

I'm mounting the body on my '40 coupe and am planning to buy some stainless bolts and washers to secure the body to the frame. Can someone please tell me what size the bolts should be? I think they are 5/16 x 18 but I'm not certain and I don't have any of the original bolts left to check by. The '40 Ford guys on here have forgotten more than I'll ever know about them and I'm hoping they see this post! Thanks for any help.

 

39 and 40 coupe bolts are the same. 5/16-24 is the correct size bolt. However, even if you find fine thread stainless bolts, I would not use them for several reasons
They are weaker.
They are more expensive.
They are not the correct bolt.
You're better off buying a body bolt kit that also has the correct pads.
All the mounting bolts are not the same length.
http://www.bobdrake.com/SearchForm.aspx?Search=body+bolt+kit
Also, make sure you buy these rubber mounts;
http://www.bobdrake.com/ItemForm.aspx?Item=78-5001
You can also find them on ebay. But, first go over to www.fordbarn.com and do a search for 40 Ford body bolts and find info. like this:
http://fordbarn.com/forum/showthread.php?t=94102&highlight=40+ford+body+bolts

 

Agreed with ^^. If you don't get the kit, I would use the zinc plated for the ones that go fully through, and a maybe regular ones for the others.

 

Thanks guys. I'll take your advice and just order the kit from Carpenter.

 

Be sure and get the rest of the body mount rubber pieces.

 

Also be aware that low grade stainless bolts may gall even with normal
torque specs. This will render them nearly impossible to unfasten
requiring them to be cut or torque broken. On a forty it would be difficult to access them. I had to grind the heads from a few of the originals
on my forty due to rust. I purchased the body bolt kit from Drake. Also
the rubber pad kit. The pads are numbered and have a printed chart to
assist with proper placement. The bolt kit does not have a guide as to
length location. There are various lengths and I will have to figure this out.

 

Thank you all for the words of wisdom. Being able to ask questions of this type on the HAMB is a huge resource. Its like being able to talk to the master mechanic on Chasing Classic Cars. If you've seen the show you know who I'm talking about - that guy is amazing, and this forum puts me in contact with guys that are just like him.

 

X2 on Mickyec comments, if you insist on using stainless, use course thread and either SS bolts or nuts not both.