Hey folks. I have two engines for my mustang. One was recovered from a wrecked 5.0 and the other is a stock 87 GT. The wrecked 5.0 was an 87 GT as well. Problem is the casting number on both blocks are not clear enough to get the numbers. The engine that is currently in my vehicle has a provision for a mechanical fuel pump. My other engine block does not. If anyone could just at least point me in the right direction here that'd be very helpful. I don't want to tear into both engines to find out the difference. All I know is the block with no mechanical fuel pump provision put out a lot more power. Thanks for your help.