What are the odds of it being my 4th gear in my trans?  I was in 4th at around the same speed when it locked up.  I also don't have the problem when i'm going through that speed in third gear.  Any thoughts?  Also wouldn't I notice it in my clutch if the fly wheel was warped?

if it is 4th gear your going to need a new main shaft in your transmission because 4th gear is 1:1. which means your crank speed is the same as your transmission, output & driveline speed. also, replacing your main in the transmission means replacing all the helical gears in th transmission. it would be a lot easier to get a new trans or upgrade to the 23 spline turbo trans. as for the flywheel/clutch warpage. if you have a dial indicator you can use that to check the out of round and warpage. otherwise use a straight edge and feeler gauges. put feeler gauge on a part of the flywheel put straight edge on top. then try to pull out the feeler gauge. if it moves the straight edge then it is smaller than that feeler gauge. check about 6 places around the flywheel.