The Ford CLT-9000 trucks were cab-over versions of the Ford L - Series (also known as the 'Louisville Line' for the city where they were built, Louisville, Kentucky). They were built from 1978 to 1991 & replaced the Ford 'W' series cabover. The numbering system used had three digit numbers for the gasoline engines (SAMPLE: C-900 & four digits for the diesel equipped trucks). The 'T' on the end of the model number meant it was a tandem axle vs. a single axle (CL-9000 vs. CLT-9000). That also applied to the conventional models (L-9000 vs. LTL-9000).
They were available with different engine/transmission combinations. SAMPLE: Caterpillar or Cummns. Eaton Roadranger transmisions with 9, 10, or more speeds. Wheelbase was also optional. If you were ordering a 'day cab' (non-sleeper) version, you wouldn't need as long a wheelbase as someone who ordered a sleeper. Additionally, there were different size sleepers available which could affect the wheelbase.