Getting columns from lines of uneven length
After you have tupls:

data = [(t[0], t[-3], t[-2], t[-1] for t in tupls] # Or use range...
print(list(zip(*data))


Gives:

[('8/5/15', '8/9/15'), ('custid', 'custid'), ('locid', 'otherlocid'), ('55.00', '79.00')]


So this:

testdata = """8/5/15 stuffidontneed custid locid 55.00
8/9/15 stuff i really dont need with extra spaces custid otherlocid 79.00"""
rows = testdata.split('\n')
tupls = [row.split(' ') for row in rows]
dates = [tupl[0] for tupl in tupls]
custids, locids, amounts = ([tupl[i] for tupl in tupls] for i in range (-3, 0))
print(dates, custids, locids, amounts)


Becomes:

testdata = """8/5/15 stuffidontneed custid locid 55.00
8/9/15 stuff i really dont need with extra spaces custid otherlocid 79.00"""
rows = testdata.split('\n')
tupls = [row.split(' ') for row in rows]
data = [(t[0], t[-3], t[-2], t[-1] for t in tupls] # Or use range...
print(list(zip(*data))