I should know how to do this but I can't figure it out. I am getting a feed from IT with following information for example. Just can't seem to format the information as I want to.

Column A Column B
113700 113621
161153 161002

I need to convert both to time. It results should look like below
Column A Column B
11:37:00 11:36:21
16:11:53 16:10:50

After this is completed, I then need to find the difference in minutes between the two columns. For example the difference of first two numbers is:
11:37:00 - 11:36:21 = 00:00:39
Column C
00:00:39

The difference of the next two numbers is:
16:11:53 - 16:10:50 = 00:01:03
Column C
00:01:03