While I am certain I do not possess the intellectual firepower or have the depth and breadth of experience with MVs as some members on this site, I do have to say that I can read and have, in fact, looked at these two manuals.
I am not as familiar with these manuals as I was with those that I used while teaching F-16 and F-15 Jet Engine Intermediate Maintenance while I was in the USAF but I was able to find the figures with this bracket listed.
The bracket in question is listed as Item #3 in each manual. Figure 174 in the -20p, and figure
209 in the -34p
Item #1 is what I understood to be the decontamination bracket that is bolted directly to the floor using screws and threaded inserts.
Item #3 is a bracket that is welded directly to the floor and is obviously a mounting point for some piece of equipment.
The -20p does not list a description for item #3 in the listing of items below the illustration.
and lists item #1 only as Bracket Assembly, CH
The -34p Lists the same description as the -20p for item #1 and describes item #3 only as Bracket Assembly, DE
There is a cross reference for these items in the cross reference section of the manual and in fact I have found the NSN listed for item #3 but there is no description there either.
Please forgive the ignorance of those of us that don't know the deep dark inner-workings of these manuals and find ourselves asking such questions as these. Given the information I could find I thought I was asking a reasonable question that would be addressed with a reasonable and helpful answer.