Aftermarket options for replacement transmission and transfer case bolts?

Being on the verge of stripping my manual transmission drain bolt led me on a hunt for something with a more robust head on it (not unlike a fine pint of porter). Ordered two replacements from the dealer since I couldn't find anything right away. Does anyone have a lead on a more substantial bolt that won't easily strip when trying to take it off? From what i understand this bolt is 74-42; 18mm-1.50, Transmission Fill Plug toyota p/n: 90341 18006

Also, would penetrating lube be ok to use on the drain bolt in the hopes it'll break loose? Possible rusted gasket. I used a torque wrench when i last did the fluid drain and fill and tightened it to 27ft/lbs. so I can't blame it on another mook at jiffylube.

 

I use an impact on mine when its stuck on there to avoid stripping it using a socket. Normally i don't like socket/allen head type fasteners, but marlin has some low profile drain plugs that are real nice and work great on my lefty.