#!/usr/bin/env perl
use strict;
use warnings;

my %part_nums = map { $_ => 1 } qw(3478749 3633731);

while ( my $line = <DATA> ) {
    my ($part) = split /:/, $line;
    print $line if exists $part_nums{$part};
}

__DATA__
3478748:AA:1D:AAA:Descriptions:C:2
3478749:AA:1D:AAA:Descriptions:C:2
3633731:AA:3E:AAA:Descriptions:C:2