I am getting ready to do a M6 to TH400 conversion in my 99SS. I was wondering what a lock-up mod is on the trans and if its worth getting. Seems to be about an extra $1000 to get a lock up trans. Thanks Jessie

Only if you are gonna keep the 4.10 gears. I have 3.42s and love the 400, btw I just swapped from an m6.

to bring this back...

what kind of rpm are you turning with the th400 an your 3.42 @ 60-90mph?

Also, can one explain how thi swould work with a th400 and how would it compare to a 4l60e lock-up. Can it be manually locked or is it electronic/hydraulic?

thanks!

a lock up is not worth it.