torque converter squeal?

My car just turned 50K and was previously owned by a 62 year old guy. Once in a while I can hear a squeal at WOT between second to third. Is this a torq converter issue?

I'm ready to take it to my local trans guy for a flush and would appreciate opinions and feedback before talking with him.

And is there anybody out there who has had any issues with the JMod? How much would a shop charge for the work?
 
This is a little funny. What you're hearing is belt slip, accessory belt slip from the momentum of the accessories. If it annoys you get a gatorback belt, but it doesn't really cause any harm.
What would lead you to think it's the TC? During a shift the TC actually has little to do with what going on as well.
 
I'm glad there's a bit of humor in this...and I don't know why I thought it would be the converter. And your point makes sense because the trans shifts very firm in other situations.

The accessory belt? I'll look into this and it will be gone by the end of the week!

Any other Jmod auto guys have any advice?