The difference(visually) is in how far away from the timing cover the back of the pump is. If the back of the wp is almost touching the timing cover, you have a "short" pump. If you can stick yer finger(s) in the gap between the pump and the cover, you have a "long" pump.
Most Corvettes had the short pump, so all of the accessory drives(P/S, A/C, etc.) would fit...
You always need to compare new with old, tho..ya never know what you may have, or what someone else has put on in the past...
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Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"