mopar intake

can anyone tell me the difference between intake 4452891 and 4452893. in hp books "how to hotrod the small block mopar" they show the 4452891 in one of their recomendations and i see a 4452893 for sale somewhere, but that number is not listed in the book under mopar manifolds. im thinking the 93 is a replacement for the 91 and if so what if any differences are there.