My aluminum three row doesn't have a draincock installed (???).  Rather than pulling the lower radiator hose every time, and making a mess, I'd like to install a draincock.  I figure this will involve drilling / tapping which is fine, but I foresee tiny shards of aluminum making their way downstream. 

 Suggestions?

You will have to take it out and have a radiator shop or someone that can tig weld aluminum.  Regarding the fear of metal shavings I am sure the shop would thoroughly flush it out as part of the repair.  Shocking that it does not have a drain **** on it.  Who is it made by?

My 77' with original rad (I think) didn't have a draincock.  I took it to a rad shop and had one installed along with a good flush.  Then I finished it out with black paint and a coat of clear. Having to pull the lower hose was never a fun job. 

The first time using the petcock (insert joke here) in two years, it failed. Petcocks are usually made of crappy brass!

The lower radiator hose method is the safest way if you don't want to risk having any issues.

Install a pet/drain-**** in the lower hose.

Thanks Hardway, yeah I'll probably take it out as you suggested. This radiator is from Arizona Z Car 11 years ago, and it is considered a racing radiator even though I don't race.  

I just gave them a call, I think I talked to the owner, and he said they do not install a draincock because they feel that it could get knocked off since the bottom of the radiator is 2 inches lower than a stock radiator. I think one could easily be installed because it still sits higher than the oil pan.

Thanks!

 

If anybody else is interested:

A little research turned up an aluminum bung to weld to the bottom of the tank:

http://www.jpcycles.com/product/721-343

And an all aluminum draincock from the Corvette guys:

http://corvettespecialty.com/corvette-aluminum-radiator-draincock-1960-72

I haven't checked on sizing yet but I imagine 3/8 being standard.