The LS1 computer has two programmable VSS outputs. The output for the ABS is by default the same pulses per mile for the ABS unit in my 95 pickup for example as for the 2002 ABS unit. If you verify the number of pulses per mile your ABS unit is expecting as an input you can program the VSS output on the new PCM to match that. One snag in the OBS trucks is the speedo operates at 2000 PPM and the radio, cruise control, etc. use 4000 PPM. There are only two VSS outputs on the LS1 PCM so you cannot drive ABS, speedo, and cruise simultaneously. You will need a converter box for the cruise or speedo.