new motor new problem

[96GST16g]

ok heres the deal i bought a motor ( said to run ) one rod is silver and three are gold... the crank has markerd numbers like a junk yards marker and i can hear air coming from the bottum of the piston when turned over by hand ( pans off ) kind of just want some input on what to do really

[1G4G63]

pics will help. Take a few pics of the rods and crank. When I take cranks to my machine shop to get some work done they usally mark numbers on the crank.

[CarPsyco84]

Kind of normal to hear air moving when you turn it over by hand... Sounds like one of the rods is new and the other 3 are old. It might vibrate more unless you had it balanced, but it will work.

[96GST16g]

think i should throw in a new rotating ass.?