I am going to purchase a L31 HD. I can't remember the part #, but it's the new GM one for $1899.00. It will be mated to a th350 original to my 71 chevy truck. Which flexplate do I use for this application? I understand it's the one for a one piece rear main seal. Maybe you could steer me in the right direction? Also, tell the boss to design some JEGS engine packages for these vortec crate engines. You have many for the old style non roller blocks, but only a few options for the roller design. Thanks!