I may be wrong, but I don't think any of the Gen1 SWB trucks had an oil cooler as original equipment. I've installed one from a LWB on my SWB, but had to make the brackets to bolt it in place on the headlight side.

Be sure to get the long bracket that goes from the driver side of the cooler to the radiator support/latch mount. Also, you'll want to get the hoses, hose banjo bolts, misc clamps, bolts, vibration standoff and the thermostatic valve for the bottom of the oil filter adapter.

All you should need to fabricate are 2 small "L" brackets to mount to the side of the headlight area.

Frank