70 gmc 6 bolt front drums

[jerryonly]

Hi i have a 70 GMC and it has the stock 6 bolt drums all the way around i want to swap axles in the back to make them 5's and possibly change the front drums to a 5 bolt pattern, just wondering if there is a year of car i can grab 5 bolt front drums off of , and also what length would my rear axles be just so i order the correct ones, some of you are probably thinking why not change the front to disk they are likely better but i just want to keep the old drums all the way around. Thanks