How to fit my rear mech?

This may seem basic, but bare with me.
I have a shimano 105 rear mech which should be affixed to the frame directly via a threaded hole beneath the dropouts. Here lies the problem; my frame does not have this threaded hole, and I just had it resprayed so I don't think taking it to a welder will be my solution. Is there a device for sorting this, or do I just need a new mech?

I can take pics if my explanation isn't good enough. The frame in question is a 531 dawes galaxy (not sure of the exact vintage, but i'd guess 70's).
Thanks.

pics please...

Do you want me to post you a new rear mech hanger that attaches to the drop-out where your wheel fits? I think this is maybe what you're looking for.

Gratis, of course.

Roddy

Seeing as I have a decent chunk of my bike (cranks, wheels, mechs) as 105 I'd hoped I could get these working together. Pics coming as soon as my computer recognises my phone

My super galaxy which has the correct fitting.

My Galaxy (the intended frame for this mech) which does not have it...

You need a replacement dropout hanger.
http://www.sjscycles.co.uk/shimano-rear-gear-hanger-bracket-fixing-bolt-prod406/
Might work.

PM me if you want a free hanger as I have a new one spare.

How to fit my rear mech? Is n't this a fixed gear forum haha I've also got a spare drop out somewhere

yeah very true, it's also why I needed help, I've only built fixies so I haven't dealt with these before. I think fixed gears are banned on some organised rides so I'm making a (hopefully nice) tourer/racer. Rodabod has kindly set me up with one, thanks for the offer though!