I did all of the spline cutting etc to my T 5 install behind my 250 in my 52 Burb, and mine wouldn't work either. I'll tell you what does work is a 1/2 inch alumunun spacer between the bellhousing and tranny. Now I have to replace the input shaft on the tranny since I cut it all up and shorted it. Much simpler to machine a spacer.!!!!