Re: oil cooler
I suppose you could run with out one, i just didn't like the idea of the oil cooking in my turbo after i beat on it for a while. I did install a turbo timmer to help out though.
The adapter plate for a normal spin on filter can be bought from gm or removed from any 4.3 junk yard vechile. It should be located on the passanger side rear part of the motor. Right now you will have the end for the remote filter bolted in. Remove the bolts, remove the remote filter system, install adapter plate, spin on filter, and you should be done.
I think its held in with 2 x 7/16th bolts, should be able to reuse them too.