How to randomly take 4 pieces out of 13 categories in excel?

I might not have the best title but here is what I need. For these 13 categories, I have 74 racks in total. I will have 12 trucks to pick up the racks throughout the day and each truck will take 5/6 racks in average and 10 racks maximum. I need to figure out a way to divide these 74 racks to 12 different orders with random mix and not so random amount. Ideas will be appreciated.

adjusted # racks

A 1 B 1 C 1 D 2 E 3 F 3 G 4 H 5 I 6 J 7 K 15 L 18 M 8