If you've got the Motorolla alt with the regulator mounted under the right step... it's dead simple to hook up the Delco.
To mount the alternator... grind some relief into the mounting bracket so the fat delco will make a full pivot. Once it's mounted... find the BAT wire and the indicator light wire in the harness. Hook the large bat wire to the BAT terminal on the alt and while you do that run a jumper to terminal 2 on the alt. Then get the indicator wire and hook that to terminal 1. I think I got terminal 1 and 2's functions correct. If not, reverse them... Then hook a case ground to the alternator and somewhere on the chassis of the tractor simply so it doesn't rely on the pivot bolts for ground. Tape up the field wire in the harness so it doesn't short out... then unplug the old regulator. You're done. That simple. You'll possibly need a different belt and pulley for the alt depending on what you have. Just MAKE SURE you get a 1/2" 'B' belt to drive it or it will slip.