I was on the TA websight and found this tech note. It appears that they have seen this crack before on the TF's. They show the 904 and not the 727 though.
Choose Tech Tips and it is #6.

http://www.turboaction.com/frame.html


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)