STI Marauder with a X300u-a... HELP!!!

I've been trying to find more info/pics on how I can make my Surefire X300u-a work on my Marauder. I've seen a few pictures that guys have mounted them, and I've tried all the mounting options but can't seem to make it work. Anyone here with a Marauder and a X300u-a or b?

Is there another way to mount the light without having to file down the serrations/stippling on the front of the grip?

Read another guy filed down the "universal" rail attachment on the light itself, but wasn't clear if it was with the quick attach or rail lock.

Any help would be great, trying to set this thing up for my HD/Bedside gun.

Thanks!!

 

The metal curved piece on back of the battery cover?

 

Ok, I'll give that a try. Thanks ChuckC!

 

Got it, thanks again. Fit's like a glove now. I saw those pins but thought they would affect the battery door. Glad it's just a spacer! Didn't want to hack things up to fit a light.