pretty difficult but you would have a much better truck when it was done.
is your gas engine a 7.5 v-8 (460) if so the transmission will need replaced
too. the cat will have an s.a.e bolt pattern don't know which one.
then you will need new mounts and the other thing is the rear
axle gears will be to low, because of the difference in top rpms
and available torque. better off to sell truck and buy another.
i have a 3208 turbo for sale if you still want to proceed.
541 990 3969 Oregon