C4 Transmission Problems

[JunkMan55]

I have a 1984 Mustang GT. I bought the car as a roller, that I put a 351W into and had someone build me a case fill 26 spline input shaft C4. When I put the transmission up to the engine block there is no room between the flexplate (brand new TCI 157 tooth) and the torque converter(brand new 10.5" from Jegs). I took the transmission to a transmission shop to install the converter and they guaranteed me the converter is in all of the way and bottomed out in the pump. My measurement from the face of the bellhousing to the mounting pads on my torque converter is only 7/8". I even measured from the deepest part of the pump to the face of the bellhousing and subtracted the total length of my torque converter and got 7/8" as my answer. So the math does not lie, my torque converter is all the way in. Does anybody have any advice for me that will help me other than "your torque converter isn't in all of the way". Because it is. Thanks!

[KevinVarnes]

Do you have the block plate installed? It won't add a ton, but it will set the trans back a touch more from the block with it installed.

[JunkMan55]

Yes I do, I have tried both an aftermarket and factory Ford plate

[JunkMan55]

Also, My transmission case is a 1968 case fill that originally had the 24 spline input shaft. When I had the transmission rebuilt I took him a 1971 and up pan fill transmission up as well and had him use the internals from the pan fill transmission in my case fill so that I could use the 26 spline input shaft. Could this be my problem? Does something not interchange??