Giovanni,
Okay, here's the info you wanted and please excuse my intrusion in your thread.
Yes, the IR filter is still available for your 3P because as Cy stated, your 3P has the same head size as a 6P. It's Surefire Part #FM33.They are expensive though! I've never had a reason to use IR other than to check motels for human stains that I stay in.
Cy is also correct that the 3W luxeon drop-in is the way to go in a 3P using a R123R. Best bang for the buck.
I really get a kick out of the old 3Ps, as they are now selling here on CPF, in the $80.00-$100.00 range! Surefire made hundreds of thousands of these things in all colors and variations and thousands with advertising laser printed on them.
All the guys here will tell you this color or that color are the rarest, believe me, they made tons of EVERY color! The advertisement marked 3P's, will be the REAL collector's items.
I get a kick whenever I see any posts on 3Ps on CPF, (again, I hope you don't mind my posting in your thread), because 3Ps are such a treasure now. Don't get me wrong, they are one of the best built SFs ever even though they had a lexan lens, (GOD FORBID!). I get a smile because they sold for $20.00-$30.00 just a little over a couple of years ago.
Heck, I sold a black, 2 silvers, two reds, a green and a blue 3P right here on CPF a couple of years ago, and never asked over $30.00 SHIPPED! When the general public gets hold of how much 3Ps are worth to the flashlight community nowadays, there will be a flood of them like no one's ever seen!
I say that's great because they'll come back down to earth pricewise and that's where they belong so the new folks on our forum can appreciate them!
Good luck with your 3P!!!