Ethan is correct. A few people installed ones similar(Not Steve's) between the transmission tailshaft and the mount and had issues(these were street and strip cars too) It also threw off the geometry of the driveshaft just a bit too.The ones I have personally seen had 1/4 plate or thicker where it goes under the mount.. I like the Metco (like the red one above) as it is more formed to the floor pan and mounts under the cross brace.Just a personal judgement
Oh yes, I understand how installing it wrong could cause issues. Installed the way it is intended shouldn’t cause any issues though, right?
I bolted mine up in between the crossmember and the Trans mount. As far as I can see, that can't be any different than a thicker crossmember. I think the entire piece is made of 1/4" steel, pretty heavy piece. I just couldn't bring myself to drill ANY holes.