I've had a GT-5 (Korean five string, "Wine" finish) a few years ago..
I bought this "used" from my bass instructor.

and have really enjoyed it..

So, when it was time for me to get "more strings".. I got another
Conklin .. This one is a GT-7 .. also Korean made, 7
string, "Natural" finish. Technically, I got this for Christmas..
but I realy did "scope this out" before buying. This one is
also "used".. I got this off of eBay, from a "InstrumentExchange.com"
seller.. which actually was a Guitar Center store in the Portland, OR
area. The gig bag that was included with it had a "sold tag" dated
in July 2005 with a customer name of it.. That with the "pristeen
condition" of the instrument.. I'm guessing that this was ordered for
a customer, and either the deal didn't complete, or the customer
returned it is "perfect" condition.. Needless to say, I'm prefectly
happy to have one if great shape.. and paid a very nice price for it.

OK, here's my situation.. I'm kind-of-a techie guy.. like to do
things on my own. I'd like to "tweek" on the truss rod on both of
these basses, and get the action just a "twinge" lower. (both are
fretted) Problem: .. these Conklin basses have a short cut-away hole
to the truss-rod adjustment. the "traditional" allen wrench has too
much "draft-on-the-shaft" to get it in there to do the job. #1. I'm
not sure what size (allen wrench) I need to use. (I hate to shorten
the shaft on an allen wrench, just to find that I did the wrong
size!) .. and not even sure if it's a "english" size or a "metric"
size wrench! 2. Is there a tool available already.. specific for the
Conklin bass truss rod?

Thanks for any suggestion!

// Brian