17mm hex. I know your not cheap Steve.. but for all of those out there that are.. get a 17mm bolt and a couple of 17mm nuts tighten em all up using the locking techique. tighten the nuts together...and poof instant 17mm allen key and a LOT cheaper.. brian On Sat, 15 Jun 2002 Calawaymk2@aol.com wrote: > What size socket is the trans drain plug? > > Steve > Callaway Turbo Scirocco #10 >