PhaseOne 645DF + M645 500mm 4.5 APO / 300mm 2.8 APO and Extension Tubes

I have my 645DF, and these two manual focus M645 lenses. I want to put an extension tube on them (especially the 500mm) to get just a little bit more close focus out of it for practical use. I have a set of the older M645 Extension tubes, but if I recall when I put them on the 645DF they did not work. Will the newer extension tubes work with the older lenses? or did I not do something correctly when using the older extension tubes with the newer camera? Thanks,

*Update*
I used the M645 tubes with the 500mm and with the 2x TC and found the following focused on the min focusing distance (5m) and then what the same focus point was at with the Tube/TC

Focus-Tube/TC Combination
5M - no Tube or TC
10m - N3S Tube
8M - N2
6M - N1
5.2M - N1 + 2x TC (Practically Unusable)