replacing text in specific location

UNIX HP-UX
1

i have a file that looks like this:

000000112/01/2008 D99999
000000 12/01/2008 D99999
000000 12/01/2008 1D99999

i need to replace the blanks into 1 for column 7,18-19

how can this be achieved using awk?

Thanks.

2

with the input sample you gave, what does the output look like?