KYB Ultra SR fitment issue
 

This is a question out of curiosity really as i have coilovers now but before i was forced to go with coilvers i bought some ultra sr's and new KYB top mounts just when putting them all together the 17mm nut would only tighten up about 40% and when i looked at the KYB shock compared to the subaru one the shaft was thicker on the KYB so wouldnt fit. Now i understand alot of owners have these with no issue so can anyone shed any light as to why i did or what i did wrong?

2004 04 sti pre widetrack

Thanks