Here's a DFSORT job that will do what I think you asked for. I assumed your input file has RECFM=FB and LRECL=80 and you want to keep the rest of the bytes in the record while expanding the PD field. You can change the job appropriately if needed. If you need more specific help, give complete details about what you want for the output records and I'll show you how to change the job.
22:22,15,ZD,TO=PD,LENGTH=8 would give you an 8-byte PD value starting at position 22. So if you had 123456789012345 as input in that field, you would get X'123456789012345C' as output for that field.
I notice you have 30,51 - that would start copying characters in the middle of your 22,15 field. I think you actually want 37,44 if you want a 73-byte output record or 37,44,80:X if you want an 80-byte output record.
If that doesn't help, then you need to show an example of your input records and the corresponding "junk" produced in the output records .