Shifter rattle, only in 3rd at 2500+ RPM

First post! Great forum, lots of good info! Couldn't find answer to my question through the search, so here it goes.

Recently, my I've been getting a weird rattle from my shifter. I think its a B&M shifter not sure, was already in the car when I got it used. The rattle is ONLY in 3rd gear, and only starts at about 2500-3000 RPM and gradually gets more violent as I continue to pull through 3rd. The rattle is somewhat superficial (doesn't have that deep vibration you'd get with out of balance driveshaft). When I put a little pressure on the shifter the rattle decreases sound wise, but something inside is still shaking. I'm thinking its something with the shifter itself, or the linkage between the shifter and tranny thats shaking the shifter around. Any thoughts?

This started happening a couple months after I got a rebuilt tranny w/ new clutch flywheel as they all went at the same time when my tranny locked up. All shifts were smooth and rattle free for a couple months..

Thanks for any input!

Thanks for the feedback!

don't remember seing any set screws/bolts on the shifter when it was out during the tranny fix. Something along the lines of the SECOND item on this page (not exactly, but similar):

http://www.innerauto.com/store/buy....me=shifter&brand_name=b-and-m&my=1&make_code=

(Unless those 4 screws around the raised shfiter thing are it?)

Maybe the set screws are just harder to find on these? Do all shifters have set screws?

Even if the set screw was nudged up a bit, doesn't this set screw affect 1st, 3rd and 5th gears, all the positions that require the shifter to be "up" or "away"? Why am I only getting the rattle in 3rd?

I'll double check my shifter after I get back from class today. Need to drop someone off to the airport anyways.

I meant the second item, i.e. the first shifter in that listing. Sorry for the confusion.