Why you shouldn't use cheap Torx bits...

[BK13]

I had that exact same failure on the diff cover bolts on my '79 CJ5. I didn't know about any better tools at the time, so I wasted about four of the CM sockets... T30 maybe?

 

[Hondarancher4435]

Much better than braking the tip off and having to drill it out of the bolt

 

[chadster1]

I have some genius torx sets for sale in the classifieds. I'd put them up against any brand.