You'll have to fab up your own mounts. Use the transmission to locate the engine, just be careful with driveline angle while doing this.
As was allready said you need a diesel trans.
This is a relatively easy swap but you will have some welding and fab work to do. Plan on removing the nose,get the largest radiator made for this truck, fab a fan shroud, return fuel line, possibly new front springs and if your going with a turbo either a body lift or you'll have to notch out the floorpan for downpipe clearance.
There's probably more that I'm forgetting but this will give you a general idea of whats involved.
Dennis