Suite Step 7 template merge on vb403 upgrade
 

I got this error when upgrading from vb402pl2 to vb403.

Fatal error: Out of memory (allocated 70778880) (tried to allocate 2642 bytes) in /home/***/public_html/vb40/includes/class_diff.php on line 170

I seem to recall a way to fix this but can't find it. A bit of code to add to a file? Any help greatly appreciated.