The first I have heard of this? And it concerns me as I am currently tearing down 2 400 Blocks to rebuild for the Duster. Do you know what years that the 400's had the thinner walls? Lets see if I can remember.....One engine I have is out of a 72 3/4 Ton truck and the other out of a 73 Newport?? I think.
This might determine what block I use for the 502 ci Stroker build later. =P~
P.S. Sorry to hijack your thread USMC1968 but the older I get the faster I have to act on questions or Ideas before I forget them. :O