Farmall Cub

The only Serial Number that I can find on the tractor is 5319 J. I'm not sure if its a 100 or 130. Any help would be nice.

Any parts that have been replaced and/or a repaint job over the last 50 yrs can throw these notes off, but...

Simplest thing is to check the engine casting number behind the oil filter, 100 should have 354898R and 130 should have 366204R. You can also check the date casting codes, for a 100 SN 5319 should be 1955 which would be an 'A', and for the 130 would be 1957 which would be a 'C' The 130 would have the center section of the grille painted white along with the inserts on the hood, while the 100 will be all red. The 130 should have the later intake manifold with curved runners vs the straight ones on the 100. We could keep going but that should be enough to get you started
HTH,
Stan