Has Anyone seen 4 BOLT MAIN CAPS ON A 2 BOLT BLOCK
 

i WENT TO A SALVAGE YARD TODAY AND PICKED UP A 454 OUT OF A 1981 GMC PICKUP. tHE FUNNY PART WAS IT HAD 4 BOLT CAPS (ALL NOT JUST MIDDLE), BUT THE OUTER HOLES WERE NOT DRILLED. wHEN I LOOKED UP THE ENGINE CODE IT SAID THIS BLOCK WAS MADE IN 2 OR 4 BOLTS. iS THIS SOMETHING CHEVY DID TO JUST MAKE 1 TYPE CAP?