71 Chevy 3/4 Ton Rear Brakes?

[1970CustomC10350]

I need to do a complete rear brake rebuild. I plan on replacing everything. I was going to order drums from LMC Truck Parts but, I'm not sure which one I need. I've been to all my local parts stores and have been asked just about everything except what color the truck is. It's a 2wd.71 3/4 ton original 396 with coil springs, HO52 axle and 4spd. Is there a difference between coil spring brakes & leaf spring brakes? Did all leaf spring trucks have the DANA 60 and which rear is heavier rated, the Dana or the HO? One store asked something about 6600 gvwr or 7200 gvwr. I ordered a chasis overhaul manual tonight so maybe that will educate me a little better. LMC has two drums to choose from. One is pn. 34-3966 described simply as rear brake drum for 3/4t 71-72 for $129.95. The other is pn. 34-3967 described rear brake drum finned for the same application for 89.95. The brake drums on the truck does have fins. Should I just order the one with fins? After being asked a variety of questions around town I am skeptical that I will get the right part the first time. They are big and I don't want to be shipping drums back and forth. Thanks for any help.