The 1999 and 2000 GMC sierra 2500 4wd with a 6.0 vortec do not
have identical replacement oil cooler lines available from GM or
aftermarket. The replacements offered required changing the
radiator fan shroud, along with other changes. Seeing that the
changes required to replace the old lines would involve
unnecessary and considerable expense, I decided to modify the
oil lines supplied by the local NAPA store, that were supposed
to fit my truck. They were several inches longer than needed,
and would not fit for that reason. To adapt the lines, I laid
the new lines on top of the old lines on a bench and determined
that the difference in length was 6 and 1/2 inches on one line,
and the other was 7 and 1/2 inches. I used a tubing cutter and
removed the excess line from each new line on the end toward the
radiator, being careful to leave enough straight tubing at the
cuts so that compression fittings could be used to join the
sections. Also, I reamed out the tubing at the cuts so that
there would be no restriction