I heard Yahoo data was shutdown,so I changed the script to use STOOQ;

assetHistory("SPY.US",FROM_STOOQ|UNADJUSTED);

I used CVStoHistory.c on the 2 .t6 files, copy and pasted in Excel, aligned date rows and saw that the datasets were pretty much the same - off by 0.01 here and there.

Wish there was a way to inspect the .t8 files.