Help, Singer 12w10 and 16-137 for chrome tanned?

[Francesco]

Couldnt find any information online regarding this two machines, can they sew 4 - 5 oz chrome tanned, crazy horse?  whats the maximum needle / thread size I can use with them?

The owner wants $130 for the 12w10 and $220 for the 16-137

 

They are also ofering me this one for $220 they only know its a singer, but not the model, any help identifying it? Which one is the best option, or none, of the three? Any guidance and help will be greatly appreciated. 

[Constabulary]

Last  picture seems to be a Singer 31 or 31K.

All theses machines are very old. The 12w most likely if the oldest from around the time when Singer took over Wheeler & Wilson. I think a 120 needle (metric) is what they all can handle but depends on the size of the needle hole in the needle plate.

Check the manuals for the machine. They should all be available online.