I believe it has a plate bolted to the trans and then the mount to the plate take up the difference between the Tremec 3550 & the T-5. I'll take a pic for you.
I don't know how to download here, but I could send you an e-mail pic, if you want to PM it to me.
Just an fyi, the height of the mount is around .250-.500" shorter to accomodate the plate that was used to relocate it......
I know this as I changed out all of my mounts with prothane's, the kit offered for the t56 has what appears to be a chevy trans mount...it was the right height, but the mounting holes that attach to the x-member were a different width, I ended up installing 2 additional weld nuts to the adapter plate, now I can use both, and it looks factory too